Fixed a distance check.

Oops, can't measure distance when locations are in different worlds.

src/me/ryanhamshire/GriefPrevention/SiegeCheckupTask.java

@@ -75,7 +75,7 @@ class SiegeCheckupTask implements Runnable
 		}
 		
 		//if they both left, but are still close together, the battle continues (check again later)
-		else if(attacker.getLocation().distanceSquared(defender.getLocation()) < 2500) //50-block radius for chasing
+		else if(attacker.getWorld().equals(defender.getWorld()) && attacker.getLocation().distanceSquared(defender.getLocation()) < 2500) //50-block radius for chasing
 		{
 			this.scheduleAnotherCheck();
 		}