- renaming the AC coding set variable names to more meaningful ones

- removed old MB decoding functions, and moved around macros to be used in
the previously unused code, which match better msmpeg4.c/whole MPV
framework
- cleaned (not yet functionnal, lots missing) DC prediction
- trying to pass the proper coded status to block decoder
patch by anonymous


git-svn-id: file:///var/local/repositories/ffmpeg/trunk@3973 9553f0bf-9b14-0410-a0b8-cfaf0461ba5b