mov: Support empty first edit + normal second edit.
mov: Support roll recovery grouping.

Frames that are a starting point of recovery are treated as keyframe and have non-zero distance since themselves are an incomplete frame.
This is useful for random accessing stream with gradual decoder refresh.
utvideodec: Support ULH0 and ULH2 formats.
riff: Support ULH0 and ULH2 fourccs.
utvideodec.c: Set colorspace by codec_tag.