Change the way region setting works.

The region now contains two location references per region point for
the bounding boxes where p1, p2, l1 and l2 remain the same (min/max),
but also additional locations for the player's actual location, such
that e.g. moving back and re-setting a point has the more intuitive
behavior of expanding regardless of the optimized points.

This also (hopefully) finally fixes the previous issues with the setup
process *knock on wood*.

src/com/garbagemule/MobArena/ArenaImpl.java

@@ -188,6 +188,7 @@ public class ArenaImpl implements Arena
     @Override
     public void setWorld(World world) {
         this.world = world;
+        if (region != null) region.refreshWorld();
     }
 
     @Override