|todo||Check if we already have an open task for this delivery?|
The subscription cycles rely on midcom.services.at. I'm not sure if it is wise to rely on it for such a totally mission critical part of OpenPSA. Some safeguards might be wise to add.
This function makes sure the new date is always in the exoected month (so in the example above it would return 2012-11-30)
integernumber of months to add
\DateTimeThe new date object