Improve performance of matrix inversion.

The inversion of scale+translate matrices was using 6 division
operations when it could be using 3. Also, general affine
matrices do not need to compute perspective components of the
matrix. This patch updates the matrix inversion with those
optimizations, and includes benchmark code to exercise those

Review URL:

git-svn-id: 2bbb7eff-a529-9590-31e7-b0007b416f81
1 file changed