[Pixman] [PATCH v10] Implement PIXMAN_FILTER_GOOD/BEST

[spitzak at gmail.com]

Changes from previous version:
- Some refactor to reduce size of each patch
- Fixed rebase error that made some patches not compile
- Renamed "scale" to "size" to avoid confusion with the transform scale

Compatibiliy notes:

For the default filter of GOOD this produces the same BILINEAR result for any scale 
greater than 3/4, and also for a scale of 1/2 if there is no rotation or translation.
For BEST the output is changed for all transforms other than the identity. For
other filter settings the result is unchanged.

These changes match those done to Cairo about 1.5 years ago, with the same amount
of incompatability. Making these changes will allow Cairo to use pixman directly
rather than generate it's own filters.