Fix MCPC+ compability for Bukkit version. Fixes #153.

Techical info: MCPC+ dynamically renames classes, fields and methods.
This means that Java's reflection cannot be used. It also has issues
with external classes extending native Minecraft classes, like
VillageGen extends StructureGenerator. Methods and fields inherited from
native Minecraft classes are renamed, but other external classes that
use those methods and fields (like BukkitWorld) aren't remapped to use
the renamed methods and fields. To get around this, a wrapper methods
and fields have been added for any external call to inherited Minecraft
methods and fields.

P.S. Terrain Control as a Forge mod is still broken on MCPC+, so launch
it as a Bukkit plugin by putting it in the plugins folder, instead of
the mod folder. I have just added extended block id support to the
Bukkit version.