Ability to add "OnZoomChanged" event listener to OpenStreetMapView instance.

[GoogleCodeExporter]

Please add an ability to be notified on zoom level change outside of 
OpenStreetMapView class. Just implement ability to add "OnZoomChanged" event 
listener to OpenStreetMapView instance. This event should be fired after:
- zoomIn;
- zoomOut;
- setZoomLevel;
- any other methods, which change map zoom level?

Original issue reported on code.google.com by vitaliy....@gmail.com on 24 Jun 2010 at 3:15