WTF's Expedition: CaveBiomes, Ores, Trees, and Tweaks

Gameplay tweaks have been spun out into a separate mod, see the various 1.5beta version changelogs for further details

Fix to compatability with mods that replace cave generation with a non-mapgencaves class instance (digimobs)

Added buffer clearing to the generation buffer.  This will cause some lag for players with high view range, set, while flying around in creative mode. But it will stop the generation buffer from overflowing and breaking.