World Generation Update

Added:
+ Secret treasure rooms now generate throughout the land! Only
accessible by bomb or other explosive device.
+ Each room contains a chest containing loot from a custom loot table
+ A single block; unbreakable except for explosions, looks exactly like
stone but you'll hear when you hit it
+ Creepers can now drop bombs

New Config Options:
+ Block id for new block (default 4080)
+ Chance (as a percent) for creepers to drop bombs
+ Max number of secret room attempts per chunk (max 10, for performance
reasons)
+ Chance (as a percent) for each iteration to generate a secret room
+ Chance (as a percent) that a heart piece will always appear in secret
room chests