Scheduler: add a possibility to cleanup executions after finishing

[bugy]

Now, all the scheduled executions stay open, until user sees them.
If a script runs quite often, it causes a lot of tabs, which a user should check, which is not very UX friendly
Also, this consumes server resources (mostly memory)
So there should be an option to mark the execution as viewed automatically

I would make it default behavior, because a user can always see execution log via history.
Except the cases, when there is an output file

[bugy]

Done. Now scheduled executions are cleaned up (i.e. removed from active executions) automatically by default. This behaviour can be disabled via scheduling.auto_cleanup = false setting in a script configuration

CC @barrelltitor this should be available on dev version

[bugy]

https://github.com/bugy/script-server/wiki/Script-config#--auto_cleanup

[barrelltitor]

It looks like I missed out on this amazing update. I'm away for the moment, but I will test this as soon as I can!

[barrelltitor]

It is working great so far! Thank you!