Accurate hit detection

With this change, hit detection for lines and points gets very
accurate, because the vector renderer instance keeps track of
line widths and point symbol sizes. After doing a bbox query in
the RTree, returned lines and points are evaluated against the
thresholds of their line width or symbol size. The KML example
with its different symbolizers now has getFeatureInfo too to
show this in action.

examples/kml.js

@@ -43,6 +43,20 @@ var map = new ol.Map({
 var kml = new ol.parser.KML({
   maxDepth: 1, dimension: 2, extractStyles: true, extractAttributes: true});
 
+map.on('mousemove', function(evt) {
+  map.getFeatureInfo({
+    pixel: evt.getPixel(),
+    layers: [vector],
+    success: function(features) {
+      var info = [];
+      for (var i = 0, ii = features.length; i < ii; ++i) {
+        info.push(features[i].get('name'));
+      }
+      document.getElementById('info').innerHTML = info.join(', ') || '&nbsp;';
+    }
+  });
+});
+
 var url = 'data/kml/lines.kml';
 var xhr = new XMLHttpRequest();
 xhr.open('GET', url, true);