fix AutoNavigation::RecenterOnBorder mode

* this mode was broken: it recentered on each position change
add constructor test
save/restore track accross restarts also in the KDE version
MarbleModel::positionTracking() always returns non-zero
reorder slots
PositionTracking
merge methods
move exportGpx() from RoutingModel to RoutingManager
move rightNeighbor() from RoutingModel to RouteRequest
RoutingModel: don't pass a MarbleModel
forward route()
move updatePosition()
RouteGuidance