Fix bug where updates for windows would check for mac updates and vise
versa.

(I am ashamed)

The 'initialize' callback is used before the encoders/output start up so
it can adjust encoder settings to required values if needed.

Also added the function 'obs_encoder_active' that returns true or false
depending on whether that encoder is active or not.

There are a ridiculous number of features related to scaling and
positioning due to requests by a number of people who complained that
they hated the way that OBS1 would always resize their sources when the
source's base size changed.  There were also people who wanted more
control for how the resizing was handled, or the ability to completely
prevent resizing entirely if desired.  So I made it so that you can
optionally use a 'bounds' system, which allows you to specify different
styles of controlling resizing.

If disabled, the source will always automatically resize and only the
base scale is applied.  If enabled, you have a variety of different ways
to limit/control how it can resize within the bounds, or make it so it
can't resize at all.  You can also control alignment within that
bounding box, so you can make it so that a source always aligns to a
side or corner of the box.

I also added an alignment value which changes how the source is oriented
relative to the position of the scene item.  For example, setting
bottom-right alignment will make it so that the position of the item is
the bottom right corner of the source.  When the source resizies, it
will resize leftward and upward in that case, which solves the problem
of how a source resizes relative to a desired position.

This way it doesn't interfere with any actual relevant commits related
to obs.h.

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.

- 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

```-----------------------------------------------
Notes and details
```

-----------------------------------------------
Why was this done?  Because wxWidgets was just lacking in many areas.  I
know wxWidgets is designed to be used with native controls, and that's
great, but wxWidgets just is not a feature-complete toolkit for
multiplatform applications.  It lacks in dialog editors, its code is
archaic and outdated, and I just feel frustrated every time I try to do
things with it.

Qt on the other hand..  I had to actually try Qt to realize how much
better it was as a toolkit.  They've got everything from dialog editors,
to an IDE, a debugger, build tools, just everything, and it's all
top-notch and highly maintained.  The focus of the toolkit is
application development, and they spend their time trying to help
people do exactly that:  make programs.  Great support, great tools,
and because of that, great toolkit.  I just didn't want to alienate any
developers by being stubborn about native widgets.

There *are* some things that are rather lackluster about it and design
choices I disagree with though.  For example, I realize that to have an
easy to use toolkit you have to have some level of code generation.
However, in my personal and humble opinion, moc just feels like a
terrible way to approach the problem.  Even now I feel like there are a
variety of ways you could handle code generation and automatic
management of things like that.  I don't like the idea of circumventing
the language itself like that.  It feels like one giant massive hack.

--------------------------------------------------
Things that aren't working properly:
--------------------------------------------------
 - Settings dialog is not implemented.  The dialog is complete but the
   code to handle the dialog hasn't been constructed yet.

 - There is a problem with using Qt widgets as a device target on
   windows, with at least OpenGL: if I have the preview widget
   automatically resize itself, it seems to cause some sort of video
   card failure that I don't understand.

 - Because of the above, resizing the preview widget has been disabled
   until I can figure out what's going on, so it's currently only a
   32x32 area.

 - Direct3D doesn't seem to render correctly either, seems that the
   viewport is messed up or something.  I'm sort of confused about
   what's going on with it.

 - The new main window seems to be triggering more race conditions than
   the wxWidgets main window dialog did.  I'm not entirely sure what's
   going on here, but this may just be existing race conditions within
   libobs itself that I just never spotted before (even though I tend to
   be very thorough with race conditions any time I use variables
   cross-thread)

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+)