- Elementary streams that scan couldn't type as audio streams have to be completely...

 - Elementary streams that scan couldn't type as audio streams have to be completely ignored - some of these don't follow the normal PES packet encoding so feeding them downstream to the demuxer will cause strange timing and other problems.
 - make log message correctly reflect our uncertainty about audio stream type so people don't complain about missing AC-3 audio when it isn't really there.
 - add missing av_free_packet in VC-1 keyframe search.

git-svn-id: svn://localhost/HandBrake/trunk@2001 b64f7644-9d1e-0410-96f1-a4d463321fa5