UI: Fix tab bars for docked widgets in Dark theme

deps/obs-scripting: Various scripting fixes

Uses the 'install' command in cmake to install scripting modules/files
(such as _obspython.so, obslua.so, and obspython.py), and changes the
install location of those files on all operating systems.  If using a
non-unix structure install, those files will be installed in
data/obs-scripting/[32bit/64bit], otherwise with unix structure installs
those files will be installed to [/usr/local/lib]/obs-scripting.

Before the new volume meters were implemented, the meter would flash red
if the audio was clipping.  This functionality was removed when the
meters were changed, whether intentionally or unintentionally, and this
patch puts that functionality back in.  If clipping occurs, the meters
will be fully colored with the foregroundErrorColor value while the
clipping is occurring.

Adds a source which tests whether audio buffering affects audio sync.
This sync test cycles through 7 audio/video frequencies at 250
millisecond intervals, and via a hotkey, will artificially move audio
time back by one second (and the audio cycle back by 4 frequencies).
This will artificially increase audio buffering by approximately 750
milliseconds.

Results from this test as of this writing: this test proves that dynamic
audio buffering does not affect sync.

This reverts commit 94b59822.

Reverting this commit because it had some negative side effects, such as
adding 500 milliseconds to the startup time.  NVENC detection should
really be done through its proper API, and not via creating an encoder
on startup.

Prevents a potential memory leak if data was previously allocated in the
frame.

A bit better handling that should prevent any possible memory leakage
due to any internal data allocated by FFmpeg.

Due to reports that the bandwidth test is randomly causing community
strikes on Youtube (likely due to bad automatic detection), the
bandwidth test will be disabled for Youtube until the Youtube API is
implemented.

Fixes an issue where text would not have language glyph fallback if
another language would used.  This problem still needs a solution on
linux/mac (and preferably a fix for language glyph fallbacks when using
freetype 2 in general).

This commit fixes a bug that occurs on Windows 8+ when two or more
"Display Capture" sources are active that are configured to capture the
same monitor.  Only one display capture would show, while all subsequent
display captures would display nothing.

Closes jp9000/obs-studio#1142

Closes jp9000/obs-studio#1141

Closes jp9000/obs-studio#1141

UI: Add the -60 volume control marker

When a scene is added as a scene item with the same audio sources that
are already in the current scene, it would cause the current scene to no
longer output audio due to audio.

To replicate the issue, you would create two separate audio device
captures in scene 1, use add existing in scene 2 and add one of those
audio sources, then go back to scene 1, add scene 2 as a source, then
make scene 1 invisible.

Value 7 was actually 5.1 surround mode, not 7.1.

There were cases where the channel format could be set to 7, which used
to be a valid format but now no longer is.  If that format is set, just
use SPEAKERS_7POINT1 instead.

Makes it a bit more clear this option shouldn't be used unless you're on
SLI/crossfire.

In the future, something should be put in to the program that detects
laptops and warns on how to set up their adapter for efficient capture.

Closes jp9000/obs-studio#1138

cmake: Add more LuaJIT lib names

Revert "CI: Add Python path for AppVeyor"

linux-pulseaudio: Default sample format float32le

This pull request changes the fallback sample format for pulse-audio
to from PA_SAMPLE_S16LE to PA_SAMPLE_FLOAT32LE.

The pulseaudio plugin can handle the following sample format:
* PA_SAMPlE_U8
* PA_SAMPLE_S16LE
* PA_SAMPLE_S32LE
* PA_SAMPLE_FLOAT32LE

When an audio device advertises itself as another format, the pulseaudio-plugin
will ask pulse audio to convert to the fallback sample format.

The fallback PA_SAMPLE_S16LE is not ideal when your audio interface advertises
as PA_SAMPLE_S24LE since the conversion will lose precision.
With PA_SAMPLE_FLOAT32LE there is no precision loss and it is also equals OBS's
internal format.

Makes building on Windows easier.

This is not necessary with the updated pre-built windows dependencies.
This reverts commit 516e9daa.

CI: Add Python path for AppVeyor

Fixes swig/python dependencies to search for the pre-compiled deps on
windows.