Renamed Point -> Point2D. Some initial work on the game loop in World (WorldTickEvent) and added additional World events for zone addition / removal  (ZoneAddedEvent / ZoneRemovedEvent)
Work on entity movement support, with a partial implementation of entity position and movement handing in EntityData2D. A Zone2DMovementTickEvent was added to facilitate this, and basic functionality for position calculation over time was stubbed out. Documentation was also updated to reflect changes.