Implement a global notification and events logging system

Certain operations can take several minutes to complete, e.g. creating a template. The proposal is as follow:

• All events (creations, deletions, edits, pending operations, etc.) are logged in a "events" pane that the user can see if desired
• This events pane only exists in memory (RAM) while the app is running; if the app is closed, all events are lost
• Most actions already display notifications, let's keep it as is
• Any non-instant action (which could takes minutes to complete) should trigger a notification when completed or if an error is encountered; of course, this should also be displayed in the events pane