libobs: Fix Monitoring devices showing input devices

Use selected color in color property label

Fix several mem leaks

libobs, UI: reset hotkey description on target rename

UI: Fix mixer dock widget minSize being too big

When the vertical volume meter was introduced it set in the OBSBasic.ui
mixer dock definition a min width/height that was valid for both
widgets. QStackedWidget hints the minimum size as the higher w/h
of its children so this workaround is necessary.

If the transition point was above or equal to 1.0, it would cause a
divide by 0 error a few lines down.  This could cause audio data to
become corrupted with NAN audio data when mixing, which can cause
certain audio encoders (namely the FFmpeg AAC encoder) to fail.

It was possible for the transition point to be above or equal to 1.0 if
the stinger media file was no longer loadable for whatever reason.

When using a macOS running on a case-sensitive filesystem, the project
build fails due to AudioToolBox/AudioQueue.h not being found.
The correct path is AudioToolbox/AudioQueue.h. Since macOS comes with a
case-insensitive filesystem by default, this is a rare ocurrence
among developers who change it to be case-sensitive.

This little change skips returning true immediately when a call to
CoreAudio fails. Instead, it uses similar behavior as further 3 calls
below this change, just checking for unfreed pointers before also
returning true.

This bug fix is to show output devices in the Advanced Audio
Settings configuration, where currently on macOS it shows erroneously
input devices.

obs-x264: Specify x264 color space for BT.601

Back in an older commit, the default YUV colorspace was changed to 601
in order to ensure correct playback in video players that ignore the
contents of the H264 header.
x264's "undef" is unfortunately not what players that don't ignore the
header expect for BT.601, resulting in incorrect colors when played
back. Setting it to "bt470bg", similar to what is specified in ffmpeg
outputs, remedies this issue.

obs-ffmpeg: Set average framerate in video stream

A leak was introduced by commit 1682d77d (July 11 2015).
This is a fix.

libobs: Handle 'in', 'out', and 'inout' keywords in shader parsers

Closes obsproject/obs-studio#1296

obs-filters: Use double-precision where viable

libobs: Copy metadata for tracks/streams when remuxing

Allows the ability to group scene items.  Groups internally are
sub-scenes, which allows the ability to add unique filters and
transforms to each group.

Allows scenes to have a custom size.  Mainly used for grouping, but can
be extended with public API later.

Prevents a potential race condition with the scene mutex.

Defers updating the scene item transform to the graphics thread to
reduce the number of transform update calls.

Fixes a bug where items that had cropping would recalculate transform
every frame.  obs_scene_item::last_width and obs_scene_item::last_height
would be set to the cropped sizes rather than the source's actual size.

Adds a simple signal reference counting function
(signal_handler_connect_ref) that makes it so that signals keep the
handler around until the all the signal itself is disconnected.  This
prevents potential crashes where a signal might try to disconnect after
a handler has already been destroyed (typically in C++ with
OBSSignalHandler helper objects, where destruction isn't guaranteed to
be predictable).

This also modifies OBSSignalHandler to use the reference-counting
connections.