yvu9 support (other planar yuv formats with other chroma subsamplings should be trivial to add, if they had a IMGFMT)
disabled broken (=new) converters (they cause random sig11)
various bugfixes


git-svn-id: file:///var/local/repositories/mplayer/trunk/postproc@6533 b3059339-0415-0410-9bf9-f77b7e298cf2