Initial work on Notifications

Also included work that prepares type solving and
link following.
Support for notifications

- Reading them
- Listing unread notifications
- Going to the item mentionned in the notification (limit support)

This is also the initial support for dynamic type solving. It
is very limited at this point, but will be extended quickly.
UI fix

- Use a page instead of a dialog for Login
- Navigate forward from news page to menu page when
  there is an error with "me", and news page keeps
  circling.