Changed API functions:
libobs: obs_reset_video

Before, video initialization returned a boolean, but "failed" is too
little information, if it fails due to lack of device capabilities or
bad video device parameters, the front-end needs to know that.

The OBS Basic UI has also been updated to reflect this API change.

This allows a programatic way of determining the type of graphics module
currently active.

This returns the name of the device, "Direct3D 11" or "OpenGL"
respectively.

I was implementing a pushing/popping attributes function like with GL,
but I realized that for our particular purposes (and actually for most
purposes) its usage was somewhat..  niche.  I may still implement
pushing/popping of attributes in the future, though right now I feel
using a function to reset the state is sufficient for our purposes.

NOTE: In texture_setimage, I had to move variables to the top of the
scope because microsoft's C compiler will give the legacy C90 error of:
'illegal use of this type as an expression'.

To sum it up, microsoft's C compiler is still utter garbage.

Rename GS_ERROR_MODULENOTFOUND to GS_ERROR_MODULE_NOT_FOUND

...I'm actually concerned that I went a bit overkill trying to prevent
backwards compatibility issues with this abstraction design, because
this is a large number of files that have to be modified just to add a
single graphics subsystem export.  Someone's going to strangle me, and
when you know that someone might strangle you, that means that you did
something wrong.  We'll have to look in to simplifying this in the
future without killing backward compatibility safety.

Getting cubemaps and volume textures from file is very unlikely to ever
happen for our purposes.

These functions were mostly related to being able to set true fullscreen
mode -- however, this has no place for our purposes, and these functions
were just sitting empty and unused, so they should be removed.

Besides, fullscreen mode only applies to the windows operating system.

This variable is currently somewhat pointless, I was originally going to
use it to tell the graphics subsystem to completely rebuild the internal
vertex buffers, but it would be bad/inefficient to allow that
functionality.

Check to make sure graphics subsystem pointer isn't null before
derefrencing, and fix bugs when creating vertex buffers from
immediate-style helpers

4x4 matrices aren't as optimal, but are much more sensible to handle
when you want to do more advanced stuff like scaling, skewing, or
inversion.

Also remove an unused variable from obs-encoder.c (via clang static
analysis)

 - Add dummy GL texture support to allow libobs texture references to be
   created for GL without

 - Add a texture_getobj function to allow the retrieval of the
   context-specific object, such as the D3D texture pointer, or the
   OpenGL texture object handle.

 - Also cleaned up the export stuff.  I realized it was all totally
   superfluous.  Kind of a dumb moment, but nice to clean it up
   regardless.

 - Add a properties window for sources so that you can now actually edit
   the settings for sources.  Also, display the source by itself in the
   window (Note: not working on mac, and possibly not working on linux).

   When changing the settings for a source, it will call
   obs_source_update on that source when you have modified any values
   automatically.

 - Add a properties 'widget', eventually I want to turn this in to a
   regular nice properties view like you'd see in the designer, but
   right now it just uses a form layout in a QScrollArea with regular
   controls to display the properties.  It's clunky but works for the
   time being.

 - Make it so that swap chains and the main graphics subsystem will
   automatically use at least one backbuffer if none was specified

 - Fix bug where displays weren't added to the main display array

 - Make it so that you can get the properties of a source via the actual
   pointer of a source/encoder/output in addition to being able to look
   up properties via identifier.

 - When registering source types, check for required functions (wasn't
   doing it before).  getheight/getwidth should not be optional if it's
   a video source as well.

 - Add an RAII OBSObj wrapper to obs.hpp for non-reference-counted
   libobs pointers

 - Add an RAII OBSSignal wrapper to obs.hpp for libobs signals to
   automatically disconnect them on destruction

 - Move the "scale and center" calculation in window-basic-main.cpp to
   its own function and in its own source file

 - Add an 'update' callback to WASAPI audio sources

Also, rename atomic functions to be consistent with the rest of the
platform/threading functions, and move atomic functions to threading*
files rather than platform* files

 - Implement OBS encoder interface.  It was previously incomplete, but
   now is reaching some level of completion, though probably should
   still be considered preliminary.

   I had originally implemented it so that encoders only have a 'reset'
   function to reset their parameters, but I felt that having both a
   'start' and 'stop' function would be useful.

   Encoders are now assigned to a specific video/audio media output each
   rather than implicitely assigned to the main obs video/audio
   contexts.  This allows separate encoder contexts that aren't
   necessarily assigned to the main video/audio context (which is useful
   for things such as recording specific sources).  Will probably have
   to do this for regular obs outputs as well.

   When creating an encoder, you must now explicitely state whether that
   encoder is an audio or video encoder.

   Audio and video can optionally be automatically converted depending
   on what the encoder specifies.

   When something 'attaches' to an encoder, the first attachment starts
   the encoder, and the encoder automatically attaches to the media
   output context associated with it.  Subsequent attachments won't have
   the same effect, they will just start receiving the same encoder data
   when the next keyframe plays (along with SEI if any).  When detaching
   from the encoder, the last detachment will fully stop the encoder and
   detach the encoder from the media output context associated with the
   encoder.

   SEI must actually be exported separately; because new encoder
   attachments may not always be at the beginning of the stream, the
   first keyframe they get must have that SEI data in it.  If the
   encoder has SEI data, it needs only add one small function to simply
   query that SEI data, and then that data will be handled automatically
   by libobs for all subsequent encoder attachments.

 - Implement x264 encoder plugin, move x264 files to separate plugin to
   separate necessary dependencies.

 - Change video/audio frame output structures to not use const
   qualifiers to prevent issues with non-const function usage elsewhere.
   This was an issue when writing the x264 encoder, as the x264 encoder
   expects non-const frame data.

   Change stagesurf_map to return a non-const data type to prevent this
   as well.

 - Change full range parameter of video scaler to be an enum rather than
   boolean

 - Implement windows monitor capture (code is so much cleaner than in
   OBS1).  Will implement duplication capture later

 - Add GDI texture support to d3d11 graphics library

 - Fix precision issue with sleep timing, you have to call
   timeBeginPeriod otherwise windows sleep will be totally erratic.

 - Split input and output audio captures so that they're different
   sources.  This allows easier handling and enumeration of audio
   devices without having to do some sort of string processing.

   This way the user interface code can handle this a bit more easily,
   and so that it doesn't confuse users either.  This should be done for
   all audio capture sources for all operating systems.  You don't have
   to duplicate any code, you just need to create input/output wrapper
   functions to designate the audio as input or output before creation.

 - Make it detect soundflower and wavtap devices as mac "output" devices
   (even though they're actually input) for the mac output capture, and
   make it so that users can select a default output capture and
   automatically use soundflower or wavtap.

   I'm not entirely happy about having to do this, but because mac is
   designed this way, this is really the only way to handle it that
   makes it easier for users and UI code to deal with.

   Note that soundflower and wavtap are still also designated as input
   devices, so will still show up in input device enumeration.

 - Remove pragma messages because they were kind polluting the other
   compiler messages and just getting in the way.  In the future we can
   just do a grep for TODO to find them.

 - Redo list property again, this time using a safer internal array,
   rather than requiring sketchy array inputs.  Having functions handle
   everything behind the scenes is much safer.

 - Remove the reference counter debug log code, as it was included
   unintentionally in a commit.

See, it can sometimes be a bit confusing.  These functions should
definitely not fail under normal circumstances, and these errors may
affect the user and/or application in some way.

LOG_ERROR should be used in places where though recoverable (or at least
something that can be handled safely), was unexpected, and may affect
the user/application.

LOG_WARNING should be used in places where it's not entirely unexpected,
is recoverable, and doesn't really affect the user/application.

Also, fixed an issue with the new conversion shader not compiling
properly on some video devices

 - Changed glMapBuffer to glMapBufferRange to allow invalidation.  Using
   just glMapBuffer alone was causing some unacceptable stalls.

 - Changed dynamic buffers from GL_DYNAMIC_WRITE to GL_STREAM_WRITE
   because I had misunderstood the OpenGL specification

 - Added _OPENGL and _D3D11 builtin preprocessor macros to effects to
   allow special processing if needed

 - Added fmod support to shaders (NOTE: D3D and GL do not function
   identically with negative numbers when using this.  Positive numbers
   however function identically)

 - Created a planar conversion shader that converts from packed YUV to
   planar 420 right on the GPU without any CPU processing.  Reduces
   required GPU download size to approximately 37.5% of its normal rate
   as well.  GPU usage down by 10 entire percentage points despite the
   extra required pass.

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.

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

Was mapping the data without unmapping the data, causing the data to
become locked

 - 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)

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+)

changed gs_draw_sprite to allow custom sizes, added output textures to the core, and adjusted the test code to accommodate the changes