Add 2sus_Burn_in_Subtitles_Handbrake

[seansusmilch]

Burns in subs so that they'll never have to be burned in on the fly when streaming. Allows for selectively burning in subs in certain situations.

Example

When a file with the following is passed to the plugin Audio: jpn Subtitles: eng

The plugin will burn in the first English subtitles with the "H.264 MKV 1080p30" handbrake preset while preserving the chapter markers with the "-m" argument, and output it in a ".mkv" container

[supersnellehenk]

Still needs test(s) :)