PixelShaderGen: Revert the part of revision f7fcf7e32d6a that forced stretching c from 0..255 to 0..256 (it's just an optimization in VideoSoftware which doesn't differ from floating point logic at all).

Fixes wrong clouds in the ZWW title screen.
Fix some potential issues when blending on EFB formats without alpha.
Clean up state transition tables.

This commit is a cherry-pick of revision 6870c1fdd55c from master to tev_fixes. Previous commits with similar but slightly incorrect changes have been reverted with this commit.