If a chunk load comes in on a chunk load or gen thread,
execute it synchronously on that thread instead of enqueueing it.
It doesn't make sense to enqueue it as that thread is then
going to future.join() it and block until it's ready anyways.
This opens risk to a deadlock if every load or gen thread is
waiting on a recursive chunk but it will never finish because
all of the threads are waiting.
If we identify an invalid offset (negative, or the header sectors),
then back up the region file and erase that specific chunks offset
data.
This will avoid crashing the server with AIOBB errors and also avoids
server owners having to consider the entire region file 'lost'.
I'm not sure what leads to this state, I can only assume write cut
off mid bits.
In this scenario, there is absolutely no way to know where the chunk
actually is in the data file without loading every
single chunk in the file. And even to do that, would be quite extreme
due to the fact the file isn't in some orderly fashion.
Since the file is backed up, the user can use a region fixer tool
externally to try to restore that single chunk. We could even
add a command to restore a chunk from a backup file in a different
commit later on. But this at least prevents the server from crashing.
The server will just generate a new chunk and move on,
after printing an error to the console about it.
Also fixed the case reported in this issue about the server
hanging when a corrupt chunk is encountered, so this issue
is now fully closed.
Resolves#1541
improved the water code so that immunity wont trigger if the entity
has the water pathfinder system active, so this improves support
for all entities that know how to behave in water.
Merged 2 EAR patches together, and removed an MCUtil method that
doesnt have a purpose anymore
