Method for getting both feature id and data.

Having to call two methods to get complete feature information (id and data) is cumbersome.  The `getFeatureInfo` method returns an object with both feature id and data.

lib/OpenLayers/Layer/UTFGrid.js

@@ -237,22 +237,26 @@ OpenLayers.Layer.UTFGrid = OpenLayers.Class(OpenLayers.Layer.Grid, {
     },
     
     /**
-     * APIProperty: getFeatureData
-     * Get feature data from UTFGrid associated with a map location.
+     * APIProperty: getFeatureInfo
+     * Get details about a feature associated with a map location.  The object
+     *     returned will have id and data properties.  If the given location
+     *     doesn't correspond to a feature, null will be returned.
      *
      * Parameters:
      * location - {<OpenLayers.LonLat>} map location
      *
      * Returns:
-     * {Object} The UTFGrid data corresponding to the given map location.
+     * {Object} Object representing the feature id and UTFGrid data 
+     *     corresponding to the given map location.  Returns null if the given
+     *     location doesn't hit a feature.
      */
-    getFeatureData: function(location) {
-        var data;
-        var info = this.getTileInfo(location);
-        if (info.tile) {
-            data = info.tile.getFeatureData(info.i, info.j);
+    getFeatureInfo: function(location) {
+        var info = null;
+        var tileInfo = this.getTileInfo(location);
+        if (tileInfo.tile) {
+            info = tileInfo.tile.getFeatureInfo(tileInfo.i, tileInfo.j);
         }
-        return data;
+        return info;
     },
 
     /**
@@ -263,10 +267,11 @@ OpenLayers.Layer.UTFGrid = OpenLayers.Class(OpenLayers.Layer.Grid, {
      * location - {<OpenLayers.LonLat>} map location
      *
      * Returns:
-     * {Object} The feature identifier corresponding to the given map location.
+     * {String} The feature identifier corresponding to the given map location.
+     *     Returns null if the location doesn't hit a feature.
      */
     getFeatureId: function(location) {
-        var id;
+        var id = null;
         var info = this.getTileInfo(location);
         if (info.tile) {
             id = info.tile.getFeatureId(info.i, info.j);