UI: Add missing va_end() call

Because groups can now be used in multiple scenes at once, it's
important that if the user wishes to ungroup a group, that they must be
able to keep the group intact if it exists in other scenes.  This
requires duplicating all scene items (as well as their hotkey/private
data) instead of just reparenting the subitems.

This fixes an issue where if the user had the group referenced in
multiple scenes, the group would become empty in other scenes.

Adds an internal function to duplicate scene item data.

UI: Remove QNetworkReply from window-basic-main.hpp

QNetworkReply was added here in commit
5ba8b09c. Qt5Network was replaced in
commits 13bed1a4 and
39d1cda4, but this one line referring to
QNetworkReply remained. Let's finally remove it.

Update macOS CI build image, target, and deps

Improve X error handling

obs-filters: Fix segfault in Compressor Filter

Once a window is invalid gl-x11::get_window_geometry will return 0
so just check if the returned geometry is a valid pointer before
trying to get its width/height.

obs_audio_data* sent to compressor_filter_audio had audio->frames == 0.
The analyze_envelope was trying to access an array at index -1 in result
of that. Just return if no samples are provided.

This fixes Mantis issue: 1261

UI: Hide preview for sources and filters where possible

* Add mbedTLS in brew install
* Update Sparkle from 1.16.0 to 1.20.0
* Update Opus from 1.1.3 to 1.2.1
* Update libogg from 1.3.2 to 1.3.3
* Update libvorbis from 1.3.5 to 1.3.6
* Update libvpx from 1.6.0 to 1.7.0
* Update Jansson from 2.9 to 2.11
* Update FFmpeg from 3.2.2 to 4.0.2

UI: Add Color Coding to Source Tree Widget

win-mf: Add missing va_end() call

This commit adds the ability to select a background color for a
scene-item, whether it's a custom color or one of eight presets.

As this is an initial implementation, it lacks theme customizability,
and it also lacks the ability for the user to set their own preset
colors, so only the hard-coded 8 are available.

UI: Add missing return statement

UI: Check pointer before the first dereference

Closes obsproject/obs-studio#1375

Contrary to what the name would have you believe, QPointer<> is not used
to delete a pointer when it leaves its specific scope.  Instead, it's
used to check to see if the pointer is still valid.  For most
QWidget-based objects, this is actually fine because QWidgets that are
assigned to layouts or other widgets will automatically be destroyed --
however, for non-widget objects, this can cause a memory leak.

This patch replaces QPointer with QScopedPointer where applicable to
prevent memory leaks.

Closes obsproject/obs-studio#1367

UI: Fix disabled items in Dark theme being too light

libobs: Log libobs bitness in crash logs

Hides the preview window for audio sources in the properties menu and
contextually in the filters menu to save on gui space.

In the Dark theme, disabled UI elements had text that was too close in
color to enabled UI elements. This commit switches them to use the
"light" palette color instead of the "lighter" palette color.

libobs-d3d11: Initialize variable to zero

This adds a confirmation dialog for streaming or recording if
there are no sources.

Closes obsproject/obs-studio#1344

libobs: Rework code for checking Mac audio device capabilities for mo…

Initialize variable (that will be used to change the resource) to zero.

Allows the ability to show a web page via CEF to the users on startup to
present and announce new features.