session: User Logged Out

This addresses an issue where Users login, do something, and get
randomly shown the login screen. If they refresh the page it shows
them authenticated as normal again. This is due to a Session ID mismatch
in `isvalidSession()`. When `refreshSession()` calls
`regenerateSession()` it's supposed regenerate the session and update
the session ID however it updates the local ID which `refreshSession()`
later does. This updates `regenerateSession()` to where it updates the
session ID and allows `refreshSession()` to update the local ID. This
deduplicates the local ID update and corrects the ID mismatch.

include/class.usersession.php

@@ -171,7 +171,7 @@ function regenerateSession(int $ttl = 120) {
         // If ttl is 0 then session is destroyed immediatetly
         $_SESSION['TTD'] = time() + $ttl; // now + ttl
         if (($id=osTicketSession::regenerate($ttl)))
-            $this->session_id = $id;
+            $this->session->session_id = $id;
         // unset TTD on the new session - new life my boy!
         unset($_SESSION['TTD']);
         return $id;