Add out of gamut color handling in LUT textures

[Brankale]

reduces DeltaE

[Brankale]

I ran experiments on the NDS Phat, NDS Lite, and GB Micro with out-of-gamut color handling, and during normal gameplay there is virtually no visible difference since 99% of the time only in-gamut colors are shown. Even the few colors that do shift are barely noticeable, even under close inspection.

So, be aware that this is just a small accuracy improvement.