Add event listeners/handlers for objects

[JBoggsy]

Right now, objects aren't really tracked right in the input link. On initialization the code scans for currently visible objects and adds them as WMEs if and only if they are light cubes. Once that is done, new objects aren't added to the input-link. The solution is to add an event handler to the World object attached to the CozmoSoar instance listening for new objects becoming visible or old ones leaving the view.