Make select interaction create its FeatureOverlay

You can now configure it with a `style` option.

examples/modify-features.js

@@ -227,12 +227,15 @@ var overlayStyle = (function() {
   };
 })();
 
+var select = new ol.interaction.Select({
+  style: overlayStyle
+});
 var overlay = new ol.FeatureOverlay({
+  features: select.getFeatures(),
   style: overlayStyle
 });
 
 var modify = new ol.interaction.Modify({ featureOverlay: overlay });
-var select = new ol.interaction.Select({ featureOverlay: overlay });
 
 var map = new ol.Map({
   interactions: ol.interaction.defaults().extend([select, modify]),