A little fix to correctly show external subtitles options when there are embedded subtitles too, because external subtitle ID is not 100, but 101, 102, etc.

Example: .mkv file with 3 subtitles:
Internal
-en: Subtitle ID 0
-es: Subtitle ID 1

External
-br: Subtitle ID 102 (2 + 100)
Enable H.264 encoding when supported by renderer. Try to seek H.264 encoding compatibility before falling back to MPEG2.
Merge origin/master