many nodes have to be checked before a tree can spawn. This causes trees to be
just a tad more sparse than intended, but greatly speeds up the map generator.
Worst case drops from thousands of nodes to test per tree type to a 5-15 nodes
per tree type.
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.
