openlayers/ol3 — pull request #445 by elemoine (2013-03-29 10:05:13+00:00)
Title: Add on and un methods to ol.Object

With this one can register and unregister event listeners using `on` and `un` on any `ol.Object` object. For example:

```
map.on('dragstart', function() { window.console.log('dragstart'); });
```