Added foreignAutoRefresh option to required fields on Author and
Purchase classes.
Added ParentWindow interface and dummy implementation.

- Implement on windows where data update is needed after a child window
is closed.
- Use dummy implementation when using a child window alone.
Implemented "add book" event with update callback.

- Changed CatalogueBooks class to implement ParentWindow interface.
- Changed CatalogueCreateBook class to extend JDialog.
- Changed CatalogueBooks class to instantiate CatalogueCreateBook on
"add book" event.
- Changed CatalogueCreateBook to calls ParentWindow update() on close.
- Changed CatalogueBooks and CatalogueCreateBook to use DISPOSE_ON_CLOSE
behavior.