Accept $g_due_date_default
Created by: hnuestedt
With this change new bugs are created with the default due date set in $g_due_date_default. As the configuration var suggests to be global also the EMailReporting-Plugin should reflect that setting.
Behaviour is now copied from bug_report_page. https://github.com/mantisbt/mantisbt/blob/f2aea91ea43834a99859655fadc2838ae0cd3144/bug_report_page.php#L182