UI: Add warning for recording to mp4 format

Closes jp9000/obs-studio#804

In some cases the result of the compatability check is wrong.
For example the format "mpegts" only shows "mpeg2video" as an
encoder even though other codecs such as h.264 are supported by
ffmpeg's muxer for that container and are used within that container
in some applications.

Closes jp9000/obs-studio#804

Closes jp9000/obs-studio#804

Closes jp9000/obs-studio#804

This changes the logic to show all encoders in the Recording tab but
only show selected supported codecs in the Streaming tab (at least with
Advanced Output Mode).  The only (to my knowledge) streaming format that
supports other formats than H264 is WebRTC, which in theory should
support H264, VP8, VP9 and HEVC.  However I don't know about any ingest
server that works well with it yet.

Closes jp9000/obs-studio#794

Closes jp9000/obs-studio#794

The commit was modified and the locale was unintentionally left out.

Closes jp9000/obs-studio#809

(Jim: Technically this should never be used without video)

Closes jp9000/obs-studio#795

Adds an exception to skip d3d10 checks for theHunter: Call of the Wild,
which fixes incompatibility with game capture.

Closes jp9000/obs-studio#801

Form layouts should laways have the setting "all non-fixed fields grow"
to make it look consistent across operating systems.

Fixes the general settings pane on mac

Closes jp9000/obs-studio#799

UI: Fix ffmpeg output file extension

obs-ffmpeg, UI: Fix compiler warnings

Some Chinese fonts (for example "STHupo") won't render any characters in
the GDI+ text source.

Closes jp9000/obs-studio#800

Also executes the program with current user privileges rather than with
elevation to prevent installation issues.

CI: Various AppVeyor build speed improvements

CI: Speedup msbuild by using all CPU cores

CI: Retry failed downloads

Add AUTHORS file