Move dev tools

Fix loaderpage

Update Italian translation

Update PO files

Add linter config

Please pycodestyle

PageEvent: Save 'sort-by' selection by model in Meta

PageEvent: let user choose talks grouping

Cleanup code

Cleanup PageList code

Cleanup navbar code

Rework UI

- Use AdwOverlayNavigationView and AdwNavigationView widgets
- Remove unused code

flatpak: bump to GNOME runtime 47

Update CHANGELOG

Rename save button

Rename the event editor save button from "Ok" to "Save". This is gives a
stronger indication of the button action.

Move delete button

Move the event editor delete button from the header bar to the bottom of
the editor. This is inspired by GNOME Calendar's event editor.

Replace GTK Dialog with Adwaita Dialog

Switch from deprecated Gtk.Dialog to Adw.Dialog. Add signals to the
event editor for the different button actions.

Show author avatar in talk detalils

more persons details,if available

parse from pentabarf and store in db more persons details.
no use in UI yet.

Fix pentabarf parsing

sfscon xml has small differences from FOSDEM's xml.
The code now handles that better