Add feeds only once to the feed_ids array (feed model), drop now unused select-db action.
Use $_SESSION['loggedin'] in favour of $_SESSION['user'] to reflect which information we do
expect from this session variable. Add nothing else than a flag, which indicates a logged in
user, to $_SESSION['loggedin'].
It's not necessary to know the current user name, since we do only have one user
per database. Same for the language setting. The database defines the front-end language.
Resolves bug where the password gets stored in the $_SESSION['user'] after a remember_me
login.
Check if a requested database can be selected. Error out if not.
This prevents automatic fallbacks to the default database.
Remove the authorized information from the session if a new database
gets selected.
Factor out logout function to reuse existing code.
