Add time margin for safer bike changing

[hator]

Currently bike is only changed [intermediate station is provided] if the tour is longer than 20 minutes. However, if it is exactly 20 minutes long no such thing happens. There is no margin of error and current routing assume ~18 km/h average speed, which can be hard to achieve on Veturilo bikes given some stop lights and traffic. Consider proposing intermediate stations for routes longer than 15-17 minutes.