[mythtv] New MPEG2 commercial-cut code ready for testing

[Geoffrey Hausheer]

Just for everyone's info,
   While debugging Cory's problem, I discovered a completely different
(and unrelated) bug that will require significant rework (and very
likely will result in slowing down the processor).  Basically,
libmpeg2 doesn't work reliably when you have 2 independant decoders
going.  This may necessitate switching back to libavcodec as the
decoder.
The second issue is that the current method of rebuilding frames will
give complete garbage if you select the B-frames 0 or 1 after a
sequence header.  Fixing this means processing the previous GOP, which
will complicate things quite a bit.  The solution may be to fully
decode every frame in order (rather than just decoding headers until a
re-encode is needed).  That would drastically slow down the
processing.  This second bug may explain Bryan's corruption, or it may
not.

Anyhow, what this means is that while I am still interested in issues
that crop up, I won't be doing any more debugging until I've resolved
these new problems.  It also may be a couple of days before I've got a
new version to be tested.

.Geoff