(This commit also modifies UI)

Changes groups to their own independent type, "group".  This allows them
to be used like other regular types, and allows the ability to reference
groups in multiple scenes.  Before, a group would always be linked to
the scene it was in.  This made it cumbersome for users to modify groups
if they had a similar group in multiple scenes (they would have to
modify each group in each scene).  Making groups like other source types
makes more sense to solve this issue so they can be referenced in
multiple scenes at once.  This also removes a significant amount of
group-specific handling code required for implementing groups in the
front-end.

One limitation however: due to the way sub-items of groups are
seamlessly modifiable and sortable as part of the whole scene, the user
cannot have multiple references to the same group within one scene.

Allows using a different source type (I.E. "group" instead of "scene").

(This commit also modifies UI)

Removes obs_scene::group_sceneitem and replaces it with
obs_scene::is_group.  Changes a number of other functions related to
groups so that a group is not inherently tied to a specific scene, and
helps allow a single group to be referenced in multiple scenes if
desired.

Allows easily/safely appending all the values of one data array to
another.

(This commit also modifies deps/libcaption)

Closes obsproject/obs-studio#1354

Fix GCC 9 Warnings

vlc-video: Dlopen libvlccore.dylib on mac OS

rtmp-services: Adding Castr.io ingests to service list

As of version 3, libvlc on macOS is linked against libvlccore
differently. Previously libvlccore was referred to via the @loader_path
macro, now @rpath is used. As such, dlopen is no longer able to find
libvlccore. Explicitly load libvlccore so that the symbols that
libvlc needs can be found.

Tested against VLC versions 2.2.8 and 3.0.3.

This function returns a char *, so it should not be const (the value is
set from a function which also returns a char *, so there is no real
reason for this to be const).

Removes a likely unintentional self-comparison.

As declared, transform_val is static inline, but it should be marked as
a static inline void since it does not return.

The loop increments i towards an unsigned type, so i should also be an
unsigned type.

UI: Add frontend event for when OBS finishes loading

This reverts commit 958167c4.

This caused certain transcoders (specifically Twitch's transcoders) to
misinterpret the data and transcode the video incorrectly.

Technically, setting the transparency value via a color property isn't
currently supported.  However, some sources/filters will set their alpha
portion of their color value to 0, which would cause the color property
to have a transparent background.  Set the alpha value to 255 for now,
at least until we properly implement support for setting transparency
via the color property (if we ever do).

With the recent change to fix showing color in the color property widget
when using different themes (b8f03791), a bug was introduced:  when
opening filters with a filter that has a color property, it would sort
of "bug out" and recreate over and over.  This is likely due to
something internally with Qt and the stacked layout.  The stacked layout
really is not necessary, so remove the stacked layout and just use the
color label directly.

UI: If group's name exist, start it from 2

libobs: prevent crash from unbounded copy and bfree

Restricts the range of the copy to count number of characters.
Changes function to strip wrapping quotes as intended.

libobs: add obs_source_frame_copy

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

Currently if you making a new group it named "Group 1" by default
instead of just "Group". This fixes it. The second group will be
named "Group 2".

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.