- startElevatorDefaultStrategy(), startElevatorImprovedStrategy() and their helper methods have been successfully:
   * migrated from class Building to class Elevator.
   * changed throughly to use a different logic. They now work with reading and changing the customers' "inElevator" and "finished" variable values, instead of removing customers from the customerList. This big effort has been done in order to allow for the comparison of the two strategies, as they both need to use the list of customers. Note: it would have been possible to create a copy of the customer list, but the chosen method feels more correct, as it allows the customer to "know" this information.
   * fixed all resulting bugs.