also remove custom serializers for switch, port variables

- Add getRoutes() to IRoutingService, dummy getRoutes() to TopologyManager - update Link to be comparable/sortable - add routeCount to Route - add cookie to RouteId - make NodeDist protected

Update to link discovery manager.  LLDPs are sent every one second; with a three second timeout on ports where links were already found.  On ports where links are not present, LLDPs are sent once in every 15 seconds.