Merge pull request #2298 from probins/props

Document that options in layers and properties in features are set as object properties

src/ol/layer/imagelayer.js

@@ -8,6 +8,9 @@ goog.require('ol.layer.Layer');
  * @classdesc
  * Server-rendered images that are available for arbitrary extents and
  * resolutions.
+ * Note that any property set in the options is set as a {@link ol.Object}
+ * property on the layer object; for example, setting `title: 'My Title'` in the
+ * options means that `title` is observable, and has get/set accessors.
  *
  * @constructor
  * @extends {ol.layer.Layer}