Auth: add logged_in_from_session hook

src/Auth.php

@@ -218,6 +218,8 @@ class Auth {
           $user->username,
           self :: $logged_method?self :: $logged_method:'unknown',
           $user->backend);
+        Hook :: trigger(
+          'logged_in_from_session', array('method' => self :: $logged_method, 'user' => $user));
         return $user;
       }
       Log::warning('Invalid user data in session, drop it');