Squashed commit of the following:

commit 29a4d3effb05a2e074cb0693316ab1977baeb0b6
Author: Andreas Huber <andih@google.com>
Date:   Mon Sep 27 12:01:32 2010 -0700

    Fully working implementation of MPEG2TSWriter (for AAC and AVC sources).

    Change-Id: I8a32a47565b647bf6c078c520e39565e08ea0d84

commit f4dec4c3899f3be393508e180d6c07e249d3335e
Author: Andreas Huber <andih@google.com>
Date:   Mon Sep 27 10:36:31 2010 -0700

    More reliable identification of MPEG2 transport streams. Don't keep scanning forever in case the stream does not have both audio and video tracks.

    Change-Id: Icc5b4e8be145b2805e8776559546a6818342aea7

commit 4fe3cc942f9b3d3cf54138b828c41214aa916dd2
Author: Andreas Huber <andih@google.com>
Date:   Mon Sep 27 08:23:39 2010 -0700

    test code

    Change-Id: I16560a17661407d06497f99ff88230724bb898af

commit 64d988b24f49f179a90fa677be11c823959e734b
Author: Andreas Huber <andih@google.com>
Date:   Thu Sep 23 14:42:52 2010 -0700

    First shot at supporting writing to an MPEG2 transport stream.

    Change-Id: Ie537939a99fa3ddc0c7661c47c18277584817c74

Change-Id: If78fd034af8f6e8ceac8dbeff96d5ecb3f6b96dc