frix vdecimate scenechange can't happen on first frame i a cycle bug
fix automatic field setting based on order not working

git-svn-id: http://vapoursynth.googlecode.com/svn/trunk@446 f9120d27-2007-6f97-8312-0f4ebfa7710f
reformat the vivtc code slightly

git-svn-id: http://vapoursynth.googlecode.com/svn/trunk@447 f9120d27-2007-6f97-8312-0f4ebfa7710f
Removed some old comments.