Fixed calculating party bonus XP when players are in different

worlds throwing errors.

src/main/java/com/gmail/nossr50/m.java

@@ -157,7 +157,11 @@ public class m {
      * @return true if the distance between <code>first</code> and <code>second</code> is less than <code>maxDistance</code>, false otherwise
      */
     public static boolean isNear(Location first, Location second, double maxDistance) {
-        if (first.distance(second) < maxDistance) {
+        if (!first.getWorld().equals(second.getWorld())) {
+            return false;
+        }
+
+        if (first.distanceSquared(second) < (maxDistance * maxDistance)) {
             return true;
         }
         else {