Adding rabid slimes

![rabid](https://cloud.githubusercontent.com/assets/7573912/4816735/41653f52-5ee2-11e4-9d9e-14806d326d7f.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 may be calmed and turned into normal slimes again by lowering their body temperature bellow 0°C (dark blue slimes or 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)

One works on baby slimes, the other works on adult slimes. I agree that we should merge them and optimise all that but that statement could apply for all of the slime code, and I don't have the energy to deal with it today.