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

[Geoffrey Hausheer]

Here we go again:
http://www.pblue.org/myth/mpeg2fix-0.13.tgz

This fixes a deadlock in replex on streams with multiple audio
streams.  i'm not 100% sure of the fix, but I think it is ok.  This
should resolve the problem Adam was having on IRC.

It also should remove all deadlock conditions.  The code should
instead abort with an assert if it detects a deadlock (which at least
tells the user what is going on, and may help debug)

The PTS wrapping code was added, though it hasn't been tested too thoroughly.

I added code which attempts to preserve the interlaced/progresive info
when rebuilding frames.  libavcodec doesn't give enough control to do
this right, so I hope the hack I put in works.  Probably needs some
user testing.

So that is it.  I now have no features I plan to add before this code
goes into myth.  I will likely begin working on the interface to
mythtranscode, and commit the changes when I'm done.

New bugs may have cropped, up, there are probably still lots of issues
(I haven't fully resolved either Bryan's or Cory's issues, and there
isn't anything in here which would do so), but any issues that I can't
debug before the final merge I'll just deal with as bugs through the
tracker.

Things which could be tackled  at some point (after the merge)
add subtitle support
add ability to rebuild a bad frame from the previous good frame
(possibly interpolate if good data is available).  This is the only
way I can fix Tom's corrupted stream problem, and it would be really
cool, but will require significant effort.
support ATSC output (as opposed to converting to PS)
enforce DVD compliance (add borders or clip to resize to a given
dimension without reencoding, and build new I-frames as needed to meet
the GOP requirements).

.Geoff