Finish remove event 'type' properties.
Finish remove event 'type' properties.

We store the event name in the `event` proeprty of an event.  In a few
places were also storing it in the `type` property.  The `type` property
wasn't used consistently and has mostly been removed.  This finishes
removing it.

This closes #703.

Kitware/geojs,OpenGeoscience/geojs,Kitware/geojs,OpenGeoscience/geojs,OpenGeoscience/geojs,Kitware/geojs