Bug fix: generate_id()
Rename FormFrame.set_style() to set_substyle()
Improve generate_id()
Implement preliminary AuthorsField(Field)

Implement very prel. ArticleJournal(Substyle)
Rename Substyle.setup_gui() to get_gui()
Rename Field.setup_gui() to get_gui(), replacing the old method by that name

Remove the self.__gui attribute from Field.
The former Field.setup_gui(), now get_gui(), returns the GUI directly after setting it up.
Update Substyle abstract methods, and implement them in ArticleJournal(Substyle)

Update Substyle template