Code 3 packets with 0 frames are now invalid, and any packet with a
 frame larger than 1275 bytes is invalid (to allow for
 repacketization).

We now store the SILK/CELT offsets so that the Opus state can
now be moved/copied elsewhere in memory without problem

New code should be cleaner and easier to tune

commit dfe4d46f9abf6b0e96e66370d428da4e283204ce
Author: Jean-Marc Valin <jean-marc.valin@octasic.com>
Date:   Mon May 2 09:59:45 2011 -0400

    SILK file list update

commit 5faf541d86445eb8ce1775ea206e88afe83c7107
Author: Jean-Marc Valin <jean-marc.valin@octasic.com>
Date:   Mon May 2 09:51:29 2011 -0400

    Makefiles update

commit f5d70b3ccbe209cc07a1a604fffca93ea34bc64b
Author: Koen Vos <koen.vos@skype.net>
Date:   Mon May 2 09:50:33 2011 -0400

    SILK stereo update and MSVC build update

With minor fixes

Barely tested

Uses a 5ms redundant CELT frame embedded into the SILK or hybrid
packet to handle the switching. It's still possible to use the
PLC-based method when no redundant packet is included.