Adjustable Z probe offset, via custom M-code
Allowable range now includes default value
use existing strings
Merge pull request #804 from MissionSt/adjustable-z-probe-offset

Adjustable Z probe offset via custom M-code
Merge branch 'Marlin_v1' of https://github.com/ErikZalm/Marlin into Marlin_v1
Merge branch 'Marlin_v1' into Marlin_v1_Mendel90