Another assignment from my "Object Oriented Programming" course
##v.1 This version of Elevator Simulation that set up the object of panel, floors, and riders. Also, function "openDoorToDisembarkRider" was added to the initial building file given by professor; and function "openDoorTo" and "board" are coded in elevator file.
##v.2 Added "disembarkRider" and "boardRider" functions to the building class. In elevator class, added "hasRiderForFloor" to check if the evevator is not empty, and "removeRider" to remove the riders from elevator.
The END.