in-pass-shadows: add customized light sort

jme3-core/src/main/java/com/jme3/light/LightList.java

@@ -219,6 +219,18 @@ public final class LightList implements Iterable<Light>, Savable, Cloneable, Jme
         }
     }
 
+    public void sort(Comparator<Light> comparator) {
+        if (listSize > 1) {
+            if (tlist == null || tlist.length != list.length) {
+                tlist = list.clone();
+            } else {
+                System.arraycopy(list, 0, tlist, 0, list.length);
+            }
+
+            SortUtil.msort(tlist, list, 0, listSize - 1, comparator);
+        }
+    }
+
     /**
      * Updates a "world-space" light list, using the spatial's local-space
      * light list and its parent's world-space light list.