Using an unbound LinkedBlockingQueue means you *have* to set core and max core thread pool size the same, as they will never go above the minimum pool size by just passing them through. So this fixes the async command executor pool to actually use 2 threads, and also cleans up other usage to be explicitly "fixed" thread pool sizes, and splits off one more in Minecraft's Util class
This patch does not appear to be doing anything useful, and may
hide errors.
Currently, the save logic does not run through this path either
so it did not do anything.
Additionally, properly implement support for handling
RegionFileSizeException in Moonrise.