added function to add director to director list

complete function to add actor to actor list

complete function to add dvd to dvd list
added function for movies

changed mvp-pattern: view can create object from the model without the
use of the preseneter

changed actorView: actorView uses objects from the model
delete function with movie (we only use dvd, movie is only to inherit)

changed package structur
added functions to save actors, directors and dvds

added memory file for actors, directors and dvds
bugfix of memory function: added serial version uid