Global.checkIfLoggedIn (referrer)
function checks if user is logged in or not if false, it redirects to the login-page but before it stores the url to jump back (if passed as argument)

Sourcecode in Global/securityFunctions.js:
1:   function checkIfLoggedIn(referrer) {
2:      if (!session.user) {
3:         // user is not logged in
4:         if (referrer)
5:            session.data.referrer = referrer;
6:         res.redirect(res.handlers.site ? res.handlers.site.members.href("login") : root.members.href("login"));
7:      }
8:      return;
9:   }