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.

Prevents another deadlock if removing the scene item triggers source
cleanup of a source with graphics resources

Prevents a double free in case the scene item was previously removed

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)

Fixes behavior with multiple desktop captures in the same scene

Also create the dispatch_queue without a name to prevent name collisions

- Add 'set_default' functions to obs-data.*.  These functions ensure
  that a paramter exists and that the parameter is of a specific type.
  If not, it will create or overwrite the value with the default setting
  instead.

  These functions are meant to be explicitly called before using any of
  the 'get' functions.  The reason why it was designed this way is to
  encourage defaults to be set in a single place/function.

  For example, ideal usage is to create one function for your data,
  "set_my_defaults(obs_data_t data)", set all the default values within
  that function, and then call that function on create/update, that way
  all defaults are centralized to a single place.

- Ensure that data passed to sources/encoders/outputs/etc is always
  valid, and not a null value.

- While I'm remembering, fix a few defaults of the main program config
  file data.

Prevent null dereferencing if data is null, instead just make the
functions return and ignore the get/set requests.

I rebuilt obs.icns. Now it corresponds to Table 5-1:

Fixes build due to missing objective c functions on some configurations

Include $ORIGIN in portable mode on unix

There were some possibilities of NULL pointer dereferencing.  Also,
changed one small function to inline.

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.

I'm doing this because I might create another data structure called
obs_data for a different purpose.  That and obs_program_data feels a bit
less vague for what it does.

Renaming obs-data.h to avoid confusion about its usage

- Move over the last of the original settings dialog code to QT.  It was
  actually a bit easier to write in the QT version.  wxWidgets was
  definitely not ideal for that because the pages would fully
  create/destroy every time.

- [Win32] Fix os_dlopen so that it only appends .dll if not present

- [MacOS] Fix name dialog text edit widget issue (it would be better if
  we could just use the list widget for editing labels, will have to
  look in to that in the future)

- Tweak the settings UI a bit more and make 30 FPS default

- Add a macro to convert a QString to a UTF-8 const char * string

- Rename build/plugins to build/obs-plugins

- Remove the last of the wxWidgets code

icon_512x512@2x	-	1024 x 1024
icon_512x512	-	512 x 512
icon_256x256@2x	-	512 x 512
icon_256x256	-	256 x 256
icon_128x128@2x	-	256 x 256
icon_128x128	-	128 x 128
icon_32x32@2x	-	64 x 64
icon_32x32	-	32 x 32
icon_16x16@2x	-	32 x 32
icon_16x16	-	16 x 16

Alternative OGL loader. GLEW was bulky, slow, and sometimes didn't do its job that well. This is the replacement.

I removed GLEW, added glLoadGen (renamed to GL here), and added implementations for all platforms. Hopefully this goes better than GLAD did.

This should have been in c1599a06

More cmake adjustments

This is because the installed versions of OBS is allways executed in the install root instead of inside the bin dir.