[eluser]Gromozeka[/eluser]
Using corresponding methods of the library:
* is_logged_in - check if user authorized on the site.
* get_user_id returns user_id if user is authorized on the site, FALSE otherwise.
* get_username returns username for authorized user, FALSE otherwise. The method makes sense only if use_username is set to TRUE in config-file; otherwise returns an empty string for every user.