Adjusts damaged stance system

Makes the system for handling damaged stance behave a bit closer to what's on master, and more forgiving of broken legs and feet.

Having two broken legs/feet will no longer make you fall over, however having two missing feet or one missing leg will still do so. 

If both legs *and* both feet are broken you will still fall over, but that's fine since you are pretty messed up anyways.

The movement penalty for damaged legs/feet also scales better.