*  Fixed SQL injection vulnerabilities in profile.php, register.php and
   moderate.php.
*  Fixed file disclosure vulnerability in admin_loader.php.
*  Switched back to using a "manual" PHP version check in install script.
*  Fixed turn_off_maintenance_mode.php (hopefully for the last time).
*  Fixed template variable pun_include potentially resulting in an infinite
   loop.
*  Fixed rare SQL error involving PUN_QUIET_VISIT and last_visit.
*  Added check to make sure guest user exists.
*  Fixed moderators being able to edit user's titles regardless of group
   permission setting.
*  Added check to make sure that a forum being edited actually exists.
*  Fixed SQL error on some setups when submitting profile/essentials as an
   admin.
*  Added check to make sure that a group being edited actually exists.
*  Fixed plugins not working when/if REQUEST_URI isn't set.