Feature: Track "seen" state

[Giszmo]

When new messages or notifications are received, those events should be shown with counters and the events themselves should be shown with a different background tone.

• The Profiles tab should show counters (New notifications + conversations with new messages).
• When selecting a profile, the Notifications and Messages tab should show counters of new notifications and conversations with new messages respectively
• When selecting the Messages tab, each conversation should show a counter of new messages.