[Pixman] [PATCH pixman] V2: Implement PIXMAN_FILTER_GOOD/BEST as convolutions

[Bill Spitzak]

This patch differs from the previous one in the following ways, to
try to address Soren's comments:

The filter names and selection are not changed. I did narrow GAUSSIAN to the 
normal cutoff software I am familiar with uses.

More comments to attempt to explain the removal of reconstruction filters.

Other changes to reduce the size of the diff.

The patch to actually make GOOD/BEST work should work with the older
version of the filter generator, if you wish to apply it independently.
It selects a reconstruction filter that produces the same result.