openlayers/ol3 — pull request #1348 by tschaub (2013-12-09 19:30:48+00:00)
Title: Dispatch beforechange events and include property name in change events 

Listeners for ol.Object changes should be able to get notified before a property value changes. To support this, a `beforechange` type event is dispatched. In addition, both `beforechange` and `change` events include the `key` (property name being changed).