This means that we don't reconstruct in 4x4 dimensions, but in
blocksize dimensions, e.g. 4x8 or 8x4. This may in some cases lead
to performance improvements. Also, if we decide to re-introduce
scalable coding support, this would fix the fact that you need to
re-scale the MV halfway the block in sub8x8 non-4x4 blocks.
See issue 1013.
Change-Id: If39c890cad20dff96635720d8c75b910cafac495
In vp9, the bottom MV would be the average of the topright and
bottomleft luma MV (instead of the bottomleft/bottomright luma MV).
See issue 993.
Change-Id: Ic91c0b195950e7b32fc26c84c04788a09321e391