Permit changing media render order as long as we're not in a tick. Removes the need to remove and re-add sprites, which was cancelling their paths.

git-svn-id: svn+ssh://src.earth.threerings.net/narya/trunk@3551 542714f4-19e9-0310-aa3c-eee0fc999fb1

src/java/com/threerings/media/AbstractMediaManager.java

@@ -163,6 +163,20 @@ public abstract class AbstractMediaManager
         }
     }
 
+    /**
+     * Called by a {@link AbstractMedia} when its render order has changed.
+     */
+    public void renderOrderDidChange (AbstractMedia media)
+    {
+        if (_tickStamp > 0) {
+            Log.warning("Egads! Render order changed during a tick.");
+            Thread.dumpStack();
+        }
+        
+        _media.remove(media);
+        _media.insertSorted(media, RENDER_ORDER);
+    }
+    
     /**
      * Calls {@link AbstractMedia#tick} on all media to give them a chance
      * to move about, change their look, generate dirty regions, and so