interlaced motion estimation

interlaced motion estimation
interlaced mpeg2 encoding
  P & B frames
  rate distored interlaced mb decission
  alternate scantable support
4mv encoding fixes (thats also why the regression tests change)
passing height to most dsp functions
interlaced mpeg4 encoding (no direct mode MBs yet)
various related cleanups
disabled old motion estimaton algorithms (log, full, ...) they will either be fixed or removed

Originally committed as revision 2638 to svn://svn.ffmpeg.org/ffmpeg/trunk