experimental upscaling mode (-sws 3)
general convolution filters support (unfinished)
bugfix for bicubic upscaling
assertion checking if defined MP_DEBUG
checking of the input/output size instead of segfault if its very large


git-svn-id: file:///var/local/repositories/mplayer/trunk/postproc@4277 b3059339-0415-0410-9bf9-f77b7e298cf2