1) Removed "Regen" mode of Dupe UUID resolver, forced safe.
Some servers who updated before we had safe mode added still had this value.
There's really no reason to keep this mode, as we've seen that vanilla
triggers this often and 99.9999999% of cases will be an actual duplicate
that needs to be deleted.
2) Made Vanilla Debug messages about dupe UUIDs and dupe uuid resolve messages
only show up if the debug.entities flag is on. This will stop server owners
from panicing from seeing these logs, and stop opening bug reports on this,
only for us to tell you "don't worry about it".
3) Avoid adding entities to world that are already added to world.
This can be triggered by anything that causes an entity to be added
to the world during the chunk load process, such as chunk conversions.
Issue #1544 was a case of this.
4) Removed debug warning about ExpiringMap.
Nothing more I know to do about this anyways. We recover from it,
stop warning to reduce noise of issues to us.
light calculations repeatedly looks up the same chunk while going
down on the Y access. Pass the chunk to it to skip many round trips
to the map lookup process.
while the gains arent as big since we have last access cache, it
should hopefully avoid many callstacks of depth and improve inlining,
as well as avoids entering a synchronized code block.
The avoiding of entering synchronized section is the main goal here.
Vanilla has risk of losing entities by causing them to be
removed from all chunks if they try to move into an unloaded chunk.
This pretty much means high chance this entity will be lost in this scenario.
There is another case that adding an entity to the world can fail if
the chunk isn't loaded.
Lots of the server is designed around addEntity never expecting to fail for these reasons,
nor is it really logical.
This change ensures the chunks are always loaded when entities are
added to the world, or a valid entity moves between chunks.
Hopefully will fix issues #1496 and #1434
