Track body wetness [WIP] [CR]

Here is my attempt at storing body wetness in its own entity and not in the morale. Unfortunately, I have done something silly and I get a crash. I am hoping it's something obvious, but breakpoints don't work for me in C::B.
Fails if `body_wetness[i]` is 0.  The "usual" way to get the sign is something from http://stackoverflow.com/questions/1903954/is-there-a-standard-sign-function-signum-sgn-in-c-c