Further fire refinements

[coyo-t]

Added comments describing what we're doing with the fire and why, as well as some other tweaks, including using only a WIDTH x 1 strip for temporary storage, and converting 2d arrays to 1d ones

[coyo-t]

I'm feeling like either all of the procedural animations should be put into their own source file (Procedural.c?) with each Tick function being exposed to other units, or have each moved into their own individual sources (Ie Procedural_Water (contains still + flowing), Procedural_Fire (both of the fire textures), ect). Latter might be a bit too overboard however.