Don't need to pass a condvar for the events EasyEvent handles on its own
Implement one-off events
Implement NavProcessor/NavCollector
Remove NavProcessor, it's redundantly redundant
Implement SDLNavOutput in terms of the new NavCollector interface.  Have the ARDrone uav library handle this.
Updates for recent changes
Control can setup loop for reading nav packets
The setup_read_nav_event() will now setup the AckEvent
Implement SDLNavOutput in terms of NavCollector