Steps to reproduce the issue

This is line 455 of sofort.php:
$modelOrder->updateStatusForOneOrder($payments[0]->virtuemart_order_id, $order_history, false);
The "False" parameter disables all notifications of custom VM plugins. Furthermore the nessessary methods are not implemented, to notificate custom plugins about a payment.

Expected result

When a customer pays by using this payment gateway, custom plugins are not notified about the action. All store-settings have to be done manually.

Actual result

Custom plugins arent informed about payments. Paypal contains the nessessary methods and is working fine.

System information (as much as possible)

Joomla 3.6.2
Virtuemart 3.0.16

Additional comments

Maybe other payment plugins miss this functionality too. Paypal is working fine, the you have emplemented this feature.