PixelShaderGen: Clean up tev compare functionality.
PixelShaderGen: Use bit shifts instead of multiplications as a small optimization.
PixelShaderGen: Remove old, mostly useless comments.

A few vague lines of comments cannot replace an afternoon reading of how TEV works.
PixelShaderGen: Cleanup and clarify bump alpha combiner inputs.
PixelShaderGen: Add a note about a random idea which should be checked with hardware tests.