Very likely I was going to refactor this class, but then stopped since
it's abstract and thus can't have any constructor... but apparently I
forgot to revert that line.
Closes#377
1. Claim creation event... this is fired once all the claim creation checks have been passed. It can be cancelled. It contains the claim and the creating player
2. Claim modification event - this is fired as the claim is modified - it cannot be cancelled. It contains the claim and the modifier...which can be null.
Use Case:
This could be used so other plugins can hook gp and perform an action if a claim is created or changed. Something as simple as logging claim creations/modifications and deletions.
