[WIP] Native jquery events

This adds a compatibility layer between GeoJS and jQuery event handling interfaces.  The GeoJS interface now requires namespacing event handlers like jQuery does it.  Otherwise, the GeoJS object `on`, `off`, and `trigger` methods work the same.   With the compatibility layer, you can now attach handlers with jQuery directly, so the following are equivalent:

```javascript
function doSomething(evt, data) {
  ...
}
$(map).on(geo.event.zoom, doSomething);
$(map).trigger(geo.event.zoom, {}, data);
```

```javascript
function doSomething(data) {
  ...
}
map.on(geo.event.zoom, doSomething);
map.trigger(geo.event.zoom, data);
```

Note the difference in call signature.  For compatibility, the GeoJS methods don't use the jQuery event objects, but I'm willing to consider changing this.  I still need to go through the code to make sure that in source handlers are properly namespaced.
Should we change our event names to something else so that it avoids the confusion?