Added status effects (and bombs)

Added to the damage system an "impart effect" system, and started with "imbue bomb".

Feeling fairly happy with how it came out, when an enemy explodes the systems engaged are:

* BulletEmitter - spawns into a location and then individual explosions are a large bullet emitted

* Bullet - explosion is just a big bullet

* DecayEffect - instead of a paticle I clone the explosion then fade it out

Outside of refactoring, the primary novel code was visual.  The extra benefit of this was that I didn't like the initial feel of one large explosion, but since it was built into bullet emitter I jammed the "shoot" frequency to 0.01 and then output 10 "bullets" sized down instead of one large one, and it feels more dynamic.  

Balancing wise this is on the weaker side, I made the emitter emit for longer based on the HP of the enemy infected... will probably revisit in the future but for now it feels fun.