Set heat hold option for after print cancel/completion

[forum999]

Option needed to tell printer to keep hotend and bed at preset temp for upto 2 minutes after print completion or cancel.

Annoying that you cancel a print due to for instance failed bed adhesion and printer and immediately turns off all heat to the unit so you have to wait for it to heat up again or desperately dash to manually reset the heats first

[CoDanny]

We'll look into this for a future release. At the moment, we rather inconvenience a bit people that want to start another print right away than risking keeping the heaters on after the user cancels a print.