v0.44.0

Added

• New TryDecodeMfro function
• New mp4ff-subslister tool replacing mp4ff-wvttlister. It supports wvtt and stpp
• File.UpdateSidx() to update or add a top level sidx box for a fragmented file
• mp4.DecStartSegmentOnMoof flag to make the Decoder interpret every moof as
  a new segment start, unless styp, sidx, or mfra boxes give that information.
• New example add-sidx shows how on can add a top-level sidx box to a fragmented file.
  It further has the option to remove unused encryption boxes, and to interpret each
  moof box as starting a new segment.
• New method MoovBox.IsEncrypted() checks if an encrypted codec is signaled

Fixed

• More robust check for mfro at the end of file
• GetTrex() return value
• Can now write PIFF uuid box that has previously been read
• Does now avoid the second parsing of senc box if the file is ot encrypted as seen in moov box.

Removed

• mp4ff-wvttlister tool removed and replaced by mp4ff-subslister