I'm hoping the other fix in 324 for the level map getting corrupted
fixes the real issue and this isn't needed anymore, but i suspect it is
will wait until more study can be done though.
Fixes#3469
Mojang implemented a cache like chunks have, but this cache
is accessed by multiple threads and is totally not safe.
So just remove it
Fixes#3466
Also missed a pooled nibble release, so slid that in there too.