Allows the ability to see whether an audio source listed in advanced
audio properties is currently active or inactive (i.e. in an inactive
scene)

Allows the ability to modify the properties of inactive audio sources
which may in scenes other than the one that is currently active.

Makes the function usable outside of just window-basic-stats.cpp.

deps/obs-scripting: Expose matrix3 & 4 to scripting

Various functions available in the scripting API aren't usable
currently since you can't create the matrix3 and matrix4 needed
for their arguments.

UI: Add option to use percent instead of dB

libobs-d3d11: Increase the frame queue capacity

Sometimes Present stalls are seen when multiple swap chains are active.
This seems to fix that.

obs-ffmpeg: UI and back-end for obs-encoded streaming over various protocols such as SRT

linux-v4l2: add support for controls

Video4Linux exposes controls for capture devices.  This commit adds
those controls to the properties window for v4l2-input devices.

CI: Fix QtNetwork in Mac packaging script

UI: Ensure OBS launches when theme is missing

This change makes it so OBS will still launch even if a theme is
missing. This change also deprecates the "CurrentTheme" config key, and
is replaced by "CurrentTheme2".

This is because a previous change to make sure OBS fell back to the
System theme in case of a missing theme had been accidentally removed.
Changing the key prevents a new version of OBS setting a theme that
doesn't exist in an older version, which would prevent that version from
launching.

obs-qsv: Add all target usage options

Using terminology from FFmpeg reference, implement:
https://www.intel.com/content/dam/www/public/us/en/documents/white-papers/cloud-computing-quicksync-video-ffmpeg-white-paper.pdf

rtmp-services: Add YouStreamer

(This commit also modifies the UI module)

CI: Fix error deleting QT network framework on OSX

CI: Fix mbedtls id in mac deploy script

obs-ffmpeg: Enable VAAPI Rate Control

libobs: Null check hotkey device on macos

CI: Fix framework symlinks when building osx app

rtmp-services: Increase FB max bitrate to 6Mbps

Allows the ability to save replays with a button rather than with the
keyboard if desired.

Closes obsproject/obs-studio#1954

Facebook Live now recommends 6000kbps for most streamers and the auto
capping is clamping users to 4000kpbs. This fixes the new suggested
setting.

Enable choosing CBR, CQP and VBR.

UI: Streaming Settings Validation On Stream Start & User Help

When we use the server error to respond to user's failing to start a
stream it is slow to return an error and unclear to the user what went
wrong. This diff introduces a simple settings check before attempting
to stream and catch and explain specific URL/key issues to the user.

In the case of preset services we check there is a Stream Key before
attempting to start a stream.

In the case of "custom" we only verify there is a URL since for some
services that's all that is required or the user may use user/password
authentication.