Added TrainDepartureRegister class with the minimum required methods; addTrainDeparture, removeDeparturesBeforeTime, getTrainDepartureByTrainNumber, getTrainDeparturesByDestination, getAllDeparturesSortedByTime.
Added TrainDepartureRegister class with the minimum required methods; addTrainDeparture, removeDeparturesBeforeTime, getTrainDepartureByTrainNumber, getTrainDeparturesByDestination, getAllDeparturesSortedByTime.