Started refactoring of class Chunk

* changed the simple lock into a read/write lock
* made the methods lock(), unlock() and isLocked() deprecated
* changed the methods lock(), unlock() and isLocked() to use the write lock of the read/write lock
* moved the static subclass Statistics into its own file and renamed it to ChunkStatistics
+ added methods get*Data() to access the backing tera arrays directly
* the following methods are now deprecated: getBlock(...), setBlock(...), getSunlight(...), setSunlight(...), getLight(...), setLight(...), getLiquid(...), setLiquid(...)
- removed method inflate()
Revert "Started refactoring of class Chunk"
This reverts commit 26c81067c2521348fbbe839b56115017f6555521.

The refactoring of the class Chunk has been moved to its own branch "chunk-refactoring".