subtitle: add interface
subtitle: add a processer using ffmpeg

TODO: ass to plain text
drawText crash on my mac
subtitle: add a test
subtitle: convert ass to plain text support
subtitle: signal contentChangeds if time and content changed
subtitle: set default name filters & max size. start=>load

to avoid to read files other than subtitle files, for e.g. video file
TODO: better way to ignore video/audio file
subtitle: add qml type
qmlplayer: add subtitle support
Merge pull request #273 from wang-bin/subtitle

Subtitle