Kittens

Added kittens! Squeeee!
Added Proc, a male cat! Squeee! (I need a description for this guy)
The baby-making is now a proc for all simple_animals. You have to call it in the Life() of a female simple_animal and define a species and a child_type for it to work, though.

![Kawaii Kittens](http://puu.sh/618Gr.dmi)