Add 3 month frequency to schedule

[swild1981]

Is your feature request related to a problem? Please describe.

I have the problem that some availability reports should be created in a 3 month period, which is no big deal, but the schedule does not allow to select a send frequency of every three month.

Describe the solution you'd like

It would be great to have a schedule which can send the selected report on every 01.01., 01.04., 01.07. and 01.10. of a year.

Thanks a lot Stephan

[mzhaase]

Why not just allow a cron expression.