Remove utilities that are unused, as well as replacing
the full chunk map with a concurrentutil implementation.
Additionally, fix the addition/removal of chunks to/from the
full chunk map so that getChunkIfLoaded correctly returns a
non-null chunk when calling the load or unload events.
Chunk system patch was refactored to take advantage of
newer ConcurrentUtil's concurrent long hash table (which
fixes hash collisions caused by chaining fastutil's long hash
and CHM's hash) plus some other minor improvements.
The chunk system was also merged with Starlight, which mostly
provides a small improvement to ThreadedLevelLightEngine#checkBlock
as the scheduling was rewritten.
