Prevents a potential cross-lock deadlock.  The UI thread would lock the
scene's mutex in obs_scene_atomic_update, then the item would lock the
graphics context to create a texture.  Meanwhile in the video thread, it
could lock the graphics context in the render loop, then lock the
scene's mutex when rendering.  When doing anything graphics-related, the
graphics context is always supposed to be locked before the scene's
mutex is supposed to be locked (it's designed that way), and the
obs_scene_atomic_update would just bypass that.

Add option in properties that let you choose how audio is mixed during
transition:
- Fade Out/Fade In (existing behavior, default)
- Crossfade

Closes jp9000/obs-studio#1028

Closes jp9000/obs-studio#1001

Replay buffer is currently only supported in simple mode.  This change
adds support to advanced mode and is, for the most part, a mirror of the
addition of replay buffer to simple mode.

Mantis-bug: https://obsproject.com/mantis/view.php?id=792

Closes jp9000/obs-studio#1019

libobs: Fix a potential divide by zero crash

UI: Fix parent window geometry loading

UI: Allow volume peak to be customized via .qss

Change 'but both were not found' to 'but neither were found.'

Closes jp9000/obs-studio#1018

With certain combinations of CMake (<3.9) and ImageMagick (>=7),
configure will silently fail setting up support for ImageMagick,
even if the user requested for it, and the build will move on
(as long as FFMPEG_AVCODEC is found).  This commit adds a check
that will stop configure in such cases.

Closes jp9000/obs-studio#1018

Since ImageMagick 7, the header path has been changed.  This commit
implements a check for the version being used, and includes the
header as is appropriate.

Special thanks to Hu.

Mantis-Bug: https://obsproject.com/mantis/view.php?id=966

Gentoo-Bug: https://bugs.gentoo.org/627520

Closes jp9000/obs-studio#1018

Closes jp9000/obs-studio#1021

UI: Add missing option to context menu

Use the Qt standard buttons in the source properties dialog to make the
UI consistent.  Also remove the right alignment of the button box to
allow Qt to align standard buttons on the left side of the dialog.

Closes jp9000/obs-studio#1013

Add 'Advanced Audio Properties' option to context menu over empty area
of the Mixer's pane.

Allows the ability to hide/unhide sources in the mixer that the user
doesn't care about or doesn't necessarily want to see (such as video
sources that have audio but don't have any audio playing).  If all
sources are hidden, the user can right-click the mixer's empty area and
choose "unhide all" via a context menu.

Closes jp9000/obs-studio#1002

Allows bringing up properties/filters/etc via right-clicking mixer items
in addition instead of only being able to click the gear icon.  Minor
QoL improvement.

Allows setting and sharing of user data for sources and scene items.

For those resolutions the last two chroma samples of every other
line would be overwritten by the last chroma samples of the previous
line (depending on sampler used), producing artifacts on the left
edge of the resulting image (e.g. any color present on the right
edge of the image would "bleed" to every other line on
the left edge)

Add fix to watch for VisibilityNotify events.

Fix XCB keyboard mapping size calculation

Uses the sink device names rather than the "Monitor of" names.

Closes jp9000/obs-studio#990

Closes jp9000/obs-studio#940

Checks if the system has Pulseaudio and enables support via the
HAVE_PULSEAUDIO flag.

Closes jp9000/obs-studio#940

Make *nix system info logging more like Windows/Mac

Closes jp9000/obs-studio#953

Closes jp9000/obs-studio#953

rtmp-services: Add looch.tv streaming platform

rtmp-services: Update ingest list for Restream.io

rtmp-services: Fix misspelled country name

This adds play/pause, restart, stop, next, and previous hotkeys to the
VLC source.

Closes jp9000/obs-studio#972

That had a misspell in a Twitch ingest server:
Col_u_mbia instead Col**o**mbia.
Incremented version.

Some encoders such as the AMD AMF encoder don't set their bitrate
property, so it gets returned as 0. This causes the new network code to
allocate a tiny buffer, resulting in output starvation and throttling
to the point of uselessness if low latency mode is also enabled.

rtmp-services: Add new twitch ingest servers

Fixes an issue where it would show the wrong error when the user entered
an invalid stream key, and logs it

Closes jp9000/obs-studio#1015

Closes jp9000/obs-studio#1015