Make Slimes fire EntityTarget events. Fixes BUKKIT-1408
When moving a misplaced chunk move tile entities too. Fixes BUKKIT-4092

When a chunk is being loaded the server checks to ensure the chunk's idea of
where it is located matches where it was located in the region file. If
these two values do not match the chunk's idea of its position is updated
and the chunk is reloaded. In vanilla minecraft this loading involves the
chunk's tile entities as well. With the change to loading player chunks
asynchronously we split loading tile entities to a separate step that takes
place after this check. Because of this tile entities are loaded with invalid
locations that result in trying to fetch block data from negative or too large
positions in the chunk's internal block storage arrays.

Because loading the tile entities is not thread safe we cannot return to
vanilla behavior here. Instead when we detect a misplaced chunk we just edit
the NBT data for the chunk to relocate the tile entities. This results in
them moving correctly with the chunk without having to actually load them
first.
Validate chunk data array lengths. Fixes BUKKIT-4093

If a chunk has somehow managed to save with arrays that are not 4096 entries
long when reading them again we will get exceptions. Checking the array
length and resizing if needed is cheap so we should do this to help avoid
crashing servers due to this error.