Replaces the battle backs with animated Earthbound ones
v0.1
Uses the earthbound background generation code from https://github.com/gjtorikian/Earthbound-Battle-Backgrounds-JS to replace your boring static backgrounds.
Each background is made up of 2 layers, each with 327 possible styles (0-326)
You can either randomly generate the background at the start of each battle, or use game variables to control the background.
TODO: Tags in Troops and Maps to set a background directly?