There were a *lot* of warnings, managed to remove most of them.

Also, put warning flags before C_FLAGS and CXX_FLAGS, rather than after,
as -Wall -Wextra was overwriting flags that came before it.

I felt like the name could cause a bit of confusion with typical
graphics viewports, so I just changed it to view instead.

Originally, the rendering system was designed to only display sources
and such, but I realized there would be a flaw; if you wanted to render
the main viewport in a custom way, or maybe even the entire application
as a graphics-based front end, you wouldn't have been able to do that.

Displays have now been separated in to viewports and displays.  A
viewport is used to store and draw sources, a display is used to handle
draw callbacks.  You can even use displays without using viewports to
draw custom render displays containing graphics calls if you wish, but
usually they would be used in combination with source viewports at
least.

This requires a tiny bit more work to create simple source displays, but
in the end its worth it for the added flexibility and options it brings.

- Add bit more documentation to some of the main headers

- Fix alignment for the size of the name string of a obs_data_item.

The API used to be designed in such a way to where it would expect
exports for each individual source/output/encoder/etc.  You would export
functions for each and it would automatically load those functions based
on a specific naming scheme from the module.

The idea behind this was that I wanted to limit the usage of structures
in the API so only functions could be used.  It was an interesting idea
in theory, but this idea turned out to be flawed in a number of ways:

 1.) Requiring exports to create sources/outputs/encoders/etc meant that
     you could not create them by any other means, which meant that
     things like faruton's .net plugin would become difficult.

 2.) Export function declarations could not be checked, therefore if you
     created a function with the wrong parameters and parameter types,
     the compiler wouldn't know how to check for that.

 3.) Required overly complex load functions in libobs just to handle it.
     It makes much more sense to just have a load function that you call
     manually.  Complexity is the bane of all good programs.

 4.) It required that you have functions of specific names, which looked
     and felt somewhat unsightly.

So, to fix these issues, I replaced it with a more commonly used API
scheme, seen commonly in places like kernels and typical C libraries
with abstraction.  You simply create a structure that contains the
callback definitions, and you pass it to a function to register that
definition (such as obs_register_source), which you call in the
obs_module_load of the module.

It will also automatically check the structure size and ensure that it
only loads the required values if the structure happened to add new
values in an API change.

The "main" source file for each module must include obs-module.h, and
must use OBS_DECLARE_MODULE() within that source file.

Also, started writing some doxygen documentation in to the main library
headers.  Will add more detailed documentation as I go.

Reduces needless code repetition and still allows for proper memory
alignment.  Cleans up the code a bit.

 - Fill in the rest of the FFmpeg test output code for testing so it
   actually properly outputs data.

 - Improve the main video subsystem to be a bit more optimal and
   automatically output I420 or NV12 if needed.

 - Fix audio subsystem insertation and byte calculation.  Now it will
   seamlessly insert new audio data in to the audio stream based upon
   its timestamp value.  (Be extremely cautious when using floating
   point calculations for important things like this, and always round
   your values and check your values)

 - Use 32 byte alignment in case of future optimizations and export a
   function to get the current alignment.

 - Make os_sleepto_ns return true if slept, false if the time has
   already been passed before the call.

 - Fix sinewave output so that it actually properly calculates a middle
   C sinewave.

 - Change the use of row_bytes to linesize (also makes it a bit more
   consistent with FFmpeg's naming as well)

- Add planar audio support.  FFmpeg and libav use planar audio for many
  encoders, so it was somewhat necessary to add support in libobs
  itself.

- Improve/adjust FFmpeg test output plugin.  The exports were somewhat
  messed up (making me rethink how exports should be done).  Not yet
  functional; it handles video properly, but it still does not handle
  audio properly.

- Improve planar video code.  The planar video code was not properly
  accounting for row sizes for each plane.  Specifying row sizes for
  each plane has now been added.  This will also make it more compatible
  with FFmpeg/libav.

- Fixed a bug where callbacks wouldn't create properly in audio-io and
  video-io code.

- Implement 'blogva' function to allow for va_list usage with libobs
  logging.

- Implement texture scaling/conversion/downloading for the main view so
  we can finally start getting data to output.

  Also, redesign how it works a bit, it will now properly wait one full
  frame for each step in the process:  rendering the main texture,
  scaling the main texture to an output texture, staging/downloading the
  ouput texture, and then outputting that staged data.  This way, the
  GPU will have more than enough time to fully complete each step.

- Fix a bug with OpenGL plugin's texture staging function.  Was using
  glBindBuffer instead of what should have been used:  glBindTexture.

- Change the naming scheme of the variables in default.effect.  It's now
  named with the idea of just "color matrix" in mind instead of "yuv
  matrix", and instead of DrawRGBToYUV, it's now just DrawMatrix.

The returned ref count was never used and the returned value doesn't
actually confer any meaning in a multithreaded environment

- Add property list callbacks to sources/outputs/encoders so that if
  necessary user interface can be automatically generated or perhaps a
  property list widget can be used for them.

- Change some of the property API names.  obs_property_list_t felt a bit
  awkward when actually using it, so I just renamed it to
  obs_properties_t.

- Removed the getdata/setdata nad getparam/setparam functions from
  sources/services, they will be superseded by the dynamic procedure
  call API.

Implement a properties definition interface to allow modules to export
general properties associated with objects of libobs.

The properties definition interface allows the option for automatic
settings UI generation (which will make simple plugins easier to develop
without the need for user interface), as well as allow real-time
property editing of values of things like sources/outputs/etc without
having to open property dialogs.  More property types can be added in
the future as needed as well.

Add the ability to be able to call and use toolkit-specific or
program-specific user interface in modules.

User interface code can be either bundled with the module, or 'split'
out in to separate libraries (recommended).

There are three reasons why splitting is recommended:

  1.) It allows plugins to be able to create custom user interface for
      each toolkit if desired.

  2.) Often, UI will be programmed in one language (the language of the
      toolkit), and core logic may be programmed in another.  This
      allows plugins to keep the languages separated if necessary.

  3.) It prevents direct linkage of UI toolkits libraries with core
      module logic.

Splitting is not required, though is recommended if you want your plugin
to be more flexible with other user interface toolkits or programs.

Will implement a generic properties lookup next, which will be used for
automatic UI handling so that plugin UI isn't necessarily required.

Scene items previously were removed by calling obs_sceneitem_destroy,
but this proved to be a potential race condition where two different
threads could try to destroy the same scene item at the same time.

Instead of doing that, reference counting is now used on scene items,
and an explicit obs_sceneitem_remove function is used instead for item
removal, which sets a 'removed' variable to ensure it can only be called
exactly one time.

The previous commit used the scene as a  parameter to check to see if
the scene item was still present within the scene before destroying, but
this was actually unnecessary because the fault was because the destroy
signal was being triggered *before* the scene's mutex locked, thus
causing a race condition.  I changed the code so that it signals after
the lock instead of before, so the scene parameter should no longer be
necessary.

Fixes a deadlock when trying to remove a source from the GUI. The scene
item signal handlers would mark the source as removed which results in
the video thread also trying to run obs_sceneitem_destroy thereby
deadlocking the video thread (and the GUI thread)

Add a fairly easy to use settings interface that can be passed to
plugins, and replaced the old character string system that was being
used before.  The new data interface allows for an easier method of
getting/altering settings for plugins, and is built to be serializable
to/from JSON.

Also, removed another wxFormBuilder file that was no longer in use.

- Added some code for FFmpeg output that I'm still playing around with.
  Right now I'm just trying to get it to output to file and try to
  understand the FFmpeg/libav APIs.  Hopefully in the future this plugin
  can be used for any sort of output to FFmpeg.

- Fixed a cast warning in audio-io.c with size_t -> uint32_t

- Renamed the 'video_info' and 'audio_info' structures to
  'video_conver_info' and 'audio_convert_info' to better represent their
  actual purpose, and to avoid confusion with 'audio_output_info' and
  'video_output_info' structures.

- Removed a few macros from obs-def.h that were at one point going to be
  used but no longer going to be used (at least for now)

Just a minor fix mostly because I noticed that I kept accidentally
forgetting to add checks to the code properly.  This is one of those
cases where macros come in useful, as macros can automate the process
and help prevent these mistakes from happening by accident.

Changed the comments to properly reflect the new callbacks, as I had
forgotten to update the comments for them both.

Also, changed "setbitrate" and "request_keyframe" return values to be
boolean.

- First, I redid the output interface for libobs.  I feel like it's
  going in a pretty good direction in terms of design.

  Right now, the design is so that outputs and encoders are separate.
  One or more outputs can connect to a specific encoder to receive its
  data, or the output can connect directly to raw data from libobs
  output itself, if the output doesn't want to use a designated encoder.
  Data is received via callbacks set when you connect to the encoder or
  raw output.  Multiple outputs can receive the data from a single
  encoder context if need be (such as for streaming to multiple channels
  at once, and/or recording with the same data).

  When an encoder is first connected to, it will connect to raw output,
  and start encoding.  Additional connections will receive that same
  data being encoded as well after that.  When the last encoder has
  disconnected, it will stop encoding.  If for some reason the encoder
  needs to stop, it will use the callback with NULL to signal that
  encoding has stopped.  Some of these things may be subject to change
  in the future, though it feels pretty good with this design so far.
  Will have to see how well it works out in practice versus theory.

- Second, Started adding preliminary RTMP/x264 output plugin code.

  To speed things up, I might just make a direct raw->FFmpeg output to
  create a quick output plugin that we can start using for testing all
  the subsystems.

Completely revamped the entire media i/o data and handlers.  The
original idea was to have a system that would have connecting media
inputs and outputs, but at a certain point I realized that this was an
unnecessary complexity for what we wanted to do.  (Also, it reminded me
of directshow filters, and I HATE directshow with a passion, and
wouldn't wish it upon my greatest enemy)

Now, audio/video outputs are connected to directly, with better callback
handlers, and will eventually have the ability to automatically handle
conversions such as 4:4:4 to 4:2:0 when connecting to an input that uses
them.  Doing this will allow the video/audio i/o handlers to also
prevent duplicate conversion, as well as make it easier/simple to use.

My true goal for this is to make output and encoder plugins as simple to
create as possible.  I want to be able to be able to create an output
plugin with almost no real hassle of having to worry about image
conversions, media inputs/outputs, etc.  A plugin developer shouldn't
have to handle that sort of stuff when he/she doesn't really need to.

Plugins will be able to simply create a callback via obs_video() and/or
obs_audio(), and they will automatically receive the audio/video data in
the formats requested via a simple callback, without needing to do
almost anything else at all.

 - Added a volume variable to the obs_source structure and implemented
   functions for manipulating source volume.

 - Added a volume variable to the audio_data structure so that the
   volume will be applied when mixing.

  Scenes will now signal via their source when an item has been added
or removed from them.

  "add" - Item added to the scene.
  Parameters:  "scene": Scene that the item was added to.
               "item":  Item that was added.

  "remove" - Item removed from the scene.
  Parameters:  "scene": Scene that the item was removed from.
               "item":  Item that was removed.

make scene items use linked list rather than array (containers are a bad habit), add a few functions for getting scene item information, also use a mutex to prevent race conditions when using the linked list

add major optimization to filter processing, and as a nice side effect, make it easier to create new filters and sources

add obs_source functions to allow name manipulation and lookup based upon name, and a few other functions related to getting/setting source information

With the permission of my fellow contributors, I'm switching obs-studio back to GPL v2+ to prevent issues between this project and the original OBS project, and for personal reasons to avoid legal ambiguity (not political reasons, I admittedly would prefer GPL v3+)