It was concluded that it would be more useful if a function that provided a data segment from
the original clip just provided a new Clip, i.e. useful things like PTS and meta is still
available in the segment. So, BytesForPTSInterval was renamed to TrimToPTSRange and now
provides a Clip. The test for this function was updated accordingly.
writing Clip.Bytes required a change to the Clip type. The Clip type now possess a slice that
references the memory in which the Frames should reference for the media. Appropriate changes have
been made to Extract and TestExtract to accomidate this change.