Tenta-Fu [CR]

Added a new martial arts style for the tentacle arm style of mutation. Name is subject and welcome to change.

Also, hurray, first attempt at a GitHub Pull Request. I'll try something more useful next time, but I figured this was an easy way to start. Thanks KA101!
Good thinking.  Now we need to take it away if the player loses all tentacles (you lose ARM_TENTACLES when going to 4/8 tentacles.  ;-) ).