Consolidate rotate files.  Add unit tests for I420
and NV12 rotate functions.  Fix remaining pitch/stride
references.
Review URL: http://webrtc-codereview.appspot.com/239001

git-svn-id: http://libyuv.googlecode.com/svn/trunk@32 16f28f9a-4ce2-e073-06de-1de4eb20be90