This code will slow the map generator down a little due to bugs therein, and is
generally still in the experimental stages, but it works and is actually quite
fast!
Most of the added code written by RealBadAngel
Also adds a couple of additional biome controls to jungle trees and conifers.
Also adds a text file describing the biome settings in a human-readable manner.
At present, this doesn't actually add anything new, it just refactors the
code to allow for more trees, and adds a bunch of biome definitions, tree
models, textures, etc. but no code to use them, yet.
Also improved the look of both a little bit, and re-balanced the spawn/growth
chances, and reduced the wait time sicne we're not using a ton of code to do
this anymore.
Also made the spawn routine clear out any leaves that are in the way of a
spawning tree's trunk, so the trunks don't look like they've been cut by
leaves.
