VP8 uses a probabilistic bool coder, not a straight bit coder.
This fixes parsing when error-resilient is set.
This commit includes a copy of libvpx's bool coder, BSD licensed.
https://bugzilla.gnome.org/show_bug.cgi?id=652694
When setting up the initial mapping just act as if the global frame
information is another partition. This saves special-casing it later in
the actual packetizing code.
