Add example, and use getFeatures in other examples

The new dedicated getfeatureinfo example shows how to combine
feature info from a WMS and a vector layer. The other examples
that previously used getFeatureInfo from vector layers now use
the more appropriate getFeatures.

examples/getfeatureinfo.js

@@ -0,0 +1,59 @@
+goog.require('ol.Map');
+goog.require('ol.RendererHint');
+goog.require('ol.View2D');
+goog.require('ol.expr');
+goog.require('ol.layer.TileLayer');
+goog.require('ol.layer.Vector');
+goog.require('ol.parser.GeoJSON');
+goog.require('ol.source.TiledWMS');
+goog.require('ol.source.Vector');
+goog.require('ol.style.Polygon');
+goog.require('ol.style.Rule');
+goog.require('ol.style.Style');
+
+
+var wms = new ol.layer.TileLayer({
+  source: new ol.source.TiledWMS({
+    url: 'http://demo.opengeo.org/geoserver/wms',
+    params: {'LAYERS': 'ne:ne'}
+  })
+});
+
+var vector = new ol.layer.Vector({
+  source: new ol.source.Vector({
+    parser: new ol.parser.GeoJSON(),
+    url: 'data/countries.geojson'
+  }),
+  style: new ol.style.Style({rules: [
+    new ol.style.Rule({
+      symbolizers: [
+        new ol.style.Polygon({
+          strokeColor: '#bada55'
+        })
+      ]
+    })
+  ]}),
+  transformFeatureInfo: function(features) {
+    return features.length > 0 ?
+        features[0].getFeatureId() + ': ' + features[0].get('name') : ' ';
+  }
+});
+
+var map = new ol.Map({
+  layers: [wms, vector],
+  renderer: ol.RendererHint.CANVAS,
+  target: 'map',
+  view: new ol.View2D({
+    center: [0, 0],
+    zoom: 1
+  })
+});
+
+map.on(['click'], function(evt) {
+  map.getFeatureInfo({
+    pixel: evt.getPixel(),
+    success: function(featureInfoByLayer) {
+      document.getElementById('info').innerHTML = featureInfoByLayer.join('');
+    }
+  });
+});