add a util function to create a random id

git-svn-id: http://svn.openlayers.org/trunk/openlayers@968 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf

lib/OpenLayers/Util.js

@@ -1081,3 +1081,17 @@ OpenLayers.Util.getArgs = function() {
     }
     return args;                               // Return the object.
 };
+
+/**
+ * @param {String} prefix String to prefix random id. If null, default
+ *                         is "id_"
+ * 
+ * @returns A unique id string, built on the passed in prefix
+ * @type String
+ */
+OpenLayers.Util.CreateID = function(prefix) {
+    if (prefix == null) {
+        prefix = "id_";
+    }
+    return prefix + Math.round(Math.random() * 10000);        
+};