Fix the examples that used our '$' method.

examples/strategy-cluster-extended.js

@@ -67,6 +67,8 @@ OpenLayers.Strategy.RuleCluster = OpenLayers.Class(OpenLayers.Strategy.Cluster,
 // global variables
 var map, vectorlayer, features, stylemap, select;
 
+var $ = OpenLayers.Util.getElement;
+
 // wrap the instanciation code in an anonymous function that gets executed
 // immeadeately
 (function(){