3dnow version of the Horizontal & Vertical Lowpass filters
mmx version of the Horizontal Default filter
mmx2 & C versions of a simple filter described in a paper from ramkishor & karan
added mode flags & quality2mode function
git-svn-id: svn://svn.mplayerhq.hu/mplayer/trunk@2160 b3059339-0415-0410-9bf9-f77b7e298cf2