notebook: use GIO directory monitors to automatically refresh on changes
notebook: use GIO directory monitors to automatically refresh on changes

Add a gio.FileMonitor to each folder in the notebook. When a change
(creation, deletion, or move) is detected in any, the notebook is
refreshed.

Based on a patch from Robert Schroll <rschroll@gmail.com>

https://bugzilla.gnome.org/show_bug.cgi?id=633419

alexey4petrov/reinteract,alexey4petrov/reinteract,alexey4petrov/reinteract