Bukkit

Include set operations on batches and use them to ensure that overlaps between batches give precedent to the earliest scheduled batch.

This will take a little bit of time because I must go carefully. Like with the dependency checks, if the design isn't correct we'll have hell.

I'm restructuring the BlockImage class and adding the above-said set ops to RegenBatch.

Set operations completed for the DependingBlockSet class. Since RegenBatch uses this internally for storage, the next step is lifting these operations to RegenBatch.