Change the mechanics of option "keyint": Now controls the GOP size directly and allows variable numbers of non-IDR I-frames within a GOP.
Remove option "idrint" and replace it with "keyint_min".
Add option "8x8mv" for the sake of completeness.
git-svn-id: svn://svn.mplayerhq.hu/mplayer/trunk@14469 b3059339-0415-0410-9bf9-f77b7e298cf2