New setting: tagged players won't be protected from PVP

An issue we've experienced with CombatTag is that players who are tagged can flee into the WorldGuard safezone that surrounds the spawn area and avoid taking damage. This behavior is fairly similar to combat logging, and seems like the sort of thing this plugin ought to prevent.

My commits add a new settings option ("blockPvpProtectionWhileTagged", set to true by default) that, when enabled, force-allows EntityDamageByEntityEvents that meet the criteria used to check if an event is PVP (the same criteria used elsewhere in the plugin.) This prevents tagged players from being protected by safezones of any nature.