Correctly modify bounds
Update example with more distinct colors and no social links
Making addIndex private
Removing the clear method from the layer

We'll want this back eventually.  But this lets us have a predictable structure
for the vector layer event object.  When we do add a clear method, we could add
a different event type that didn't come with features and extent.  At the same
time, we can give this vector event object a more specific name.
Separate add listener from method that adds index
Rename method
Extent now always comes with change event

In the future, we will want to have events that don't come with extent.  To handle this, we should add a new event type instead of allowing the extent property to be undefined on the event object.