a little shader cleanup
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Code cleanup: FrameSink & WebGLFrameSink

Move some software YCbCr-specific out of OgvPlayer, wrap the
software and GPU output methods in the same API.

Note this means we no longer get separate color & draw times,
which should be fine.
drop now-unused color time from stats
drop colorTime from Flash version as well

merge yuv & drawing time into one to match current JS