Renamed PNs and PNEds. Finised open/save. Restructured PNEditors.

-> Restructured PNEditors and defined Cancelation and Finalization PNEditors better.
-> Renamed PNs and PNEditors to simply name the type of rules (Decomposition, Execution, Finalization, Cancelation).
-> Finished open/save (along with some bug fixes) in main fail.