- add empty constructore to AudioNode to reenable serialization (temp fix)

git-svn-id: https://jmonkeyengine.googlecode.com/svn/trunk@7362 75d07b2b-3a1a-0410-a2c5-0572b91ccdca

engine/src/core/com/jme3/audio/AudioNode.java

@@ -59,7 +59,7 @@ import java.io.IOException;
  */
 public class AudioNode extends Node {
 
-    protected final AudioRenderer renderer;
+    protected AudioRenderer renderer;
 
     protected boolean loop = false;
     protected float volume = 1;
@@ -104,6 +104,9 @@ public class AudioNode extends Node {
         Stopped,
     }
 
+    public AudioNode() {
+    }
+
     /**
      * Creates a new <code>AudioNode</code> without any audio data set.
      *