Fixed issue with #2154
Also moved selection of base icon for limbs to update_mutantrace so it's only doen when race is changed.
Changed mob icons a little, to get rid of rogue red pixel on torso that was not covered by arm
Moved awkward red spot where missing hand would be to arm sprite, since missing whole arm would still make stump appear there, and it looks weird.
Merge pull request #2523 from comma/master

Fixed issue with #2154