Do not render selected features on the original layer

See #1796 for a discussion on how to handle this in a better
way.

examples/modify-features.js

@@ -182,6 +182,18 @@ var realDataLayer = new ol.layer.Vector({
   style: styleFunction
 });
 
+// FIXME Handle this elsewhere - this is only to not render selected features
+// on the original layer
+vectorLayer.setRenderGeometryFunctions(new ol.Collection([function(geometry) {
+  var selected = select.getFeatures().getArray();
+  for (var i = 0, ii = selected.length; i < ii; ++i) {
+    if (selected[i].getGeometry() === geometry) {
+      return false;
+    }
+  }
+  return true;
+}]));
+
 var overlayStyle = (function() {
   var styles = {};
   styles['Polygon'] = [