Removing detritus left over from recent commits.

This removes the ChunkletUnloader class, which means that there is one less task ticking for mcMMO. This class, and its dependents, were unnecessary due to recent changes in how mcMMO deals with chunk loading and saving. Those changes drastically reduced I/O overhead, as well as how often chunks are loaded from file. As such, the ChunkletUnloader was mostly unnecessary, and actually proving to be a hindrance to tracking entities across chunk unloads.