Add overhauled illumination, fix bow item render.

![Image](http://puu.sh/cu8SU.jpg)

Illuminations now replace the block they hit. 

An illumination block can have all 1-6 sides illuminated (or 0, but that state should rarely exist, and never render).

This means that most of the complicated meta code is gone! However, the ACTUAL meta of the block MUST remain that of the block it encapsulates, so that it renders correctly. The "meta" of the illumination is stored in the "sides" field in the illumination TE.