Handler.MouseWheel gets destroy(). Fixes #600. Look out now.

git-svn-id: http://svn.openlayers.org/trunk/openlayers@2937 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf

lib/OpenLayers/Handler/MouseWheel.js

@@ -36,6 +36,15 @@ OpenLayers.Handler.MouseWheel.prototype = OpenLayers.Class.inherit( OpenLayers.H
         this.wheelListener = this.onWheelEvent.bindAsEventListener(this);
     },
 
+    /**
+     * 
+     */    
+    destroy: function() {
+        this.deactivate();
+        this.wheelListener = null;
+        OpenLayers.Handler.prototype.destroy.apply(this, arguments);
+    },
+
     /**
      *  Mouse ScrollWheel code thanks to http://adomas.org/javascript-mouse-wheel/
      */