Making it so the navigation control zooms out on two touch taps. r=erilem (closes #3127)

git-svn-id: http://svn.openlayers.org/trunk/openlayers@11537 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf

lib/OpenLayers/Control/Navigation.js

@@ -163,6 +163,7 @@ OpenLayers.Control.Navigation = OpenLayers.Class(OpenLayers.Control, {
         }
 
         var clickCallbacks = { 
+            'click': this.defaultClick,
             'dblclick': this.defaultDblClick, 
             'dblrightclick': this.defaultDblRightClick 
         };
@@ -189,6 +190,18 @@ OpenLayers.Control.Navigation = OpenLayers.Class(OpenLayers.Control, {
                                     this.mouseWheelOptions );
     },
 
+    /**
+     * Method: defaultClick
+     *
+     * Parameters:
+     * evt - {Event}
+     */
+    defaultClick: function (evt) {
+        if (evt.lastTouches && evt.lastTouches.length == 2) {
+            this.map.zoomOut();
+        }
+    },
+
     /**
      * Method: defaultDblClick 
      *