Prepares the who's online data for the Who template.

• Uses the Who template (main sub template.) and language file.
• Requires the who_view permission.
• Is enabled with the who_enabled ("Enable Who's Online list?") setting.
• Is accessed via ?action=who.
• $allowedActions sets up all the permission info for the "whoallow" items in the form of 'action' => array('permission'[,'anotherpermission'[,...]])