Certain windows functions may allow 0 as a valid handle value, therefore
INVALID_HANDLE_VALUE is a more appropriate initialization value.

Closes obsproject/obs-studio#1519

ui: Emit STREAMING_STOPPING when stop queued

When calling obs_display_set_background_color, the value set in the
'color' parameter should always be used as-is.  0 should not indicate a
color other than black.  To do anything otherwise is silly and confusing
for users of the API.

Closes obsproject/obs-studio#1516

decklink: Initialize member variable

CI: Use proper VLC release tarball

As noted by ePirat, the VLC releases on GitHub are not official
releases, just repo snapshots. Use the official VLC 3.0.4 release
tarball to ensure maximum stability.

CI: Use VLC 3.0.4 instead of master for macOS

Fixes an issue where macOS builds on Travis would fail due to changes
in VLC master branch.

libobs: memset() the correct buff size

Fixes a bug where audio panning would always be processed even if
panning was centered (and thus inactive).

AppVeyor recently updated their Qt version to 5.11.2 which breaks
builds, because of the outdated path. Using this path should always
ensure that the newest subversion of Qt 5.11 gets used.

If there's a delay, it will *also* be ommitted after the appropriate
number of seconds.

I was originally going to add a new event for this, however this is
consistent with STREAMING_STARTING, which is emitted at the start
of the delay, not the end.

This allows multiple audio tracks for the FFmpeg output.

Closes obsproject/obs-studio#1351

Closes obsproject/obs-studio#1304

Closes obsproject/obs-studio#1507

Closes obsproject/obs-studio#1506

enc-amf: Update to 2.5.0.1 and update repository address

UI: Fix typo with resize output text

This reverts commit 5edeaa30, reversing
changes made to 0d280819.

Decklink: Add decklink output

UI: Fix auto remux warning

This fixes the QAbstractItemModel invalid index warning.

UI: Change resize output text

enc-amf: Update to 2.5.0 and update repository address

Closes obsproject/obs-studio#1499

rtmp-services: Add DLive

Closes obsproject/obs-studio#1482
Closes obsproject/obs-studio#1256

linux-capture: Fix repeated color-swapping and improve robustness further

Based on:

http://dailycommit.blogspot.com/2016/10/how-to-generate-pkg-config-file-with.html
https://people.freedesktop.org/~dbn/pkg-config-guide.html

Should allow third party plugins to find and use libobs more easily.

Closes obsproject/obs-studio#1467

The text for resizing the output based on source is inaccurate
because base and canvas are the same thing.