straightened control flow for handleTransit so that the QLink does not have to reach back into the QueueWithBuffer. Saves one interface method. Special treatment of one-link-routes (for TransitDrivers) into the TransitDriver (it will answer chooseNextLinkId with null now, consistent with other agents), even though the route is encoded startLink==endLink. Criterion if agent wants to end trip is now only chooseNextLinkId==null, for everybody. Corrected a not quite true comment.