Implement FFMPEG::AudioStream
Refactor FFMPEG::Movie to use FFMPEG::VideoStream
Refactor FFMPEG::Movie to use FFMPEG::AudioStream
Deprecate all convenience methods on Movie

All convenience methods on Movie that are just pointers to methods on
the first VideoStream or AudioStream have been marked for deprecation.
Deprecate all convenience methods on Movie
Integrate Movie with VideoStream
Deprecation stuff