- the application now uses only the default values from the app.options dict, the app.defaults dict holds the definitive default values

- fixed some outstanding issues from the PyQt6 port
- PEP8 fixes
- minor fixes
- updated the saving of Preferences to update the self.options too: the `Apply` action will update the self.options but the `Save` action will save the updated preferences to the file on disk

tclCommands/TclCommandExportGerber.py

@@ -48,5 +48,5 @@ class TclCommandExportGerber(TclCommand):
         :return:
         """
         if 'filename' not in args:
-            args['filename'] = self.app.defaults["global_last_save_folder"] + '/' + args['name']
+            args['filename'] = self.app.options["global_last_save_folder"] + '/' + args['name']
         self.app.f_handlers.export_gerber(use_thread=False, **args)