Creates new "chaos magicarp" that fires a random projectile each time

*This is @Incoming5643's baby. If he doesn't like it then it probably shouldn't be merged.*

I added a new mob called "chaos magicarp" which are like normal magicarp, except they have 75 health up from 50 and fire a random magic bolt each time instead of choosing one from the start and sticking with it like the magicarp do.

I also made it randomize from ```initial(projectiletype)``` instead of directly from ```/obj/item/projectile/magic``` so someone can make a guncarp in the future without much hassle.

![chaoscarp_graph](https://cloud.githubusercontent.com/assets/5211576/4249710/c0e17a2a-3a7a-11e4-8199-11e27f649eb2.png)