Follow-up improvements for #897

* Interaction is no goog.Disposable any more.
* Permanent cleanup during selection instead of disposeInternal.
* Moved selectionLayers creation outside feature loop.
* Maintain selectedFeatures and unselectedFeatures only for
  layers that have a setRenderIntent method.

src/ol/interaction/interaction.js

@@ -2,7 +2,6 @@
 
 goog.provide('ol.interaction.Interaction');
 
-goog.require('goog.Disposable');
 goog.require('ol.MapBrowserEvent');
 goog.require('ol.animation.pan');
 goog.require('ol.animation.rotate');
@@ -13,12 +12,9 @@ goog.require('ol.easing');
 
 /**
  * @constructor
- * @extends {goog.Disposable}
  */
 ol.interaction.Interaction = function() {
-  goog.base(this);
 };
-goog.inherits(ol.interaction.Interaction, goog.Disposable);
 
 
 /**