Adding rabid slimes

![rabid](https://cloud.githubusercontent.com/assets/7573912/4816700/e65209d8-5ee1-11e4-965e-b2f4c3f49e06.png)

* The Red Slime Extract + Blood reaction will now actually make slimes rabid! When rabid they behave like any hostile monster.
* Player-controlled slimes may now be tamed with docility potions. However the slime will be the one who gets to choose his name.
* Tame slimes can become rabid, unless they are player controlled (more to code later in that aspect)
* Rabid slimes maybe be calmed and turned into normal slimes again by lowering their body temperature bellow 0°C (a temperature gun really comes handy there)
* Slimes spawned from killed adult slimes will be rabid. (they were supposed to be rabid according to the half-implemented rabid code)