Omit changing shadows for texturing

No idea how difficult it would be to implement this.

But it would be awesome if RC could somehow figure out if on some images parts of the surface are in deep shadows (almost black). And if this area has “normal” (as in comparable to the surroundings) color information, then use that and do no use those black areas for textuning.

This wouldn’t only be very handy for indoor scenes ahot with a flash but if a bit more sophisticated could improve changing shadows on outdoor scenes as well.