-Created Vector class in model to hold the displacement vector
-Updated TourMode Class to populate the list of onscreen points and
compute the displacement vector that is compensated for camera rotation. 
-Added method to user class to get the bearing between the user and a
given POI. 
-Refactored Waypoint class to POI class to give it better name. 
-Edited CompassController class to use methods in user class for
calculations