Maps of the Unknown

Added dynamic structure locating!

• Prevent world freeze while searching for a structure
• Requires the player to keep the map in hand until locating finished
• Can be toggle with the doBetterMapsDynamicLocating gamerule (default to true)

Other changes:

• loot table can now set a specific dimension for the map to be used in. Can be useful for modpack creators to make maps to specific structures harder to acquire.