Give Layer.Vector a proper clone() method. r=crschmidt (closes #2391)

git-svn-id: http://svn.openlayers.org/trunk/openlayers@9942 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf

lib/OpenLayers/Layer/Vector.js

@@ -302,6 +302,36 @@ OpenLayers.Layer.Vector = OpenLayers.Class(OpenLayers.Layer, {
         OpenLayers.Layer.prototype.destroy.apply(this, arguments);  
     },
 
+    /**
+     * Method: clone
+     * Create a clone of this layer.
+     * 
+     * Note: Features of the layer are also cloned.
+     *
+     * Returns:
+     * {<OpenLayers.Layer.Vector>} An exact clone of this layer
+     */
+    clone: function (obj) {
+        
+        if (obj == null) {
+            obj = new OpenLayers.Layer.Vector(this.name, this.options);
+        }
+
+        //get all additions from superclasses
+        obj = OpenLayers.Layer.prototype.clone.apply(this, [obj]);
+
+        // copy/set any non-init, non-simple values here
+        var features = this.features;
+        var len = features.length;
+        var clonedFeatures = new Array(len);
+        for(var i=0; i<len; ++i) {
+            clonedFeatures[i] = features[i].clone();
+        }
+        obj.features = clonedFeatures;
+
+        return obj;
+    },    
+    
     /**
      * Method: refresh
      * Ask the layer to request features again and redraw them.  Triggers