Fix "PHP Warning: session_write_close(): Failed to write session data (user)" errors

- Changed returning true when there's a session ID but no session data
in ref_session_write()
- Moved session.php requires around

boot.php

@@ -1,5 +1,7 @@
 <?php
 
+require_once 'include/session.php';
+
 require_once 'vendor/autoload.php';
 
 set_time_limit(0);