Feature request: unschedule job without cancelling running jobs

[ThomasHeijtink]

It would be nice to be able to unschedule jobs and specify whether you want runnings jobs to finish, or whether you want running jobs to be cancelled.

The current behaviour seems to be that unscheduling a job causes running jobs to be cancelled. This is unexpected as the name is unschedule doesn't seem to communicate that. Adding an extra argument would communicate this better.