events

I am working on a websocket version, and I needed events. This adds some minimal events to track what is happening.You can use them like this:

```javascript
$('#bigpicture')
    .on('bpupdate', function(e, el){
      console.log('update', el);
    })
    .on('bpnew', function(e, x, y, size, text){
      console.log('new', x, y, size, text);
    })
    .on('bpzoom', function(e, zoom, wx, wy, sx, sy){
      console.log('zoom', zoom, wx, wy, sx, sy)
    });
```