allow handlers to be attached to editor and view events

```
Events are registered with jsdot.addEventHandler and triggered with 
jsdot.fireEvent.

This can easily be exposed on the API.

When the basic editor features are implemented and the view gets updated in 
response to editor and model events this ticket can be closed.
```

Original issue reported on code.google.com by `silh...@gmail.com` on 19 Jul 2010 at 11:43
