PATH: fast retraction and return speeds for grbl_post G83 expansion #3725
PATH: fast retraction and return speeds for grbl_post G83 expansion #3725

Ensure fast retraction and then plunge to just short off previous drilled depth at G0.  Fixes painfully slow air drilling which makes peck drilling impracticable.
https://forum.freecadweb.org/viewtopic.php?f=15&t=25604&p=435639#p435639
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