Add z_offset to safe_z in end of homing Z

[DikkieKlijn]

I have disabled the docking of clicky after homing to speed up print startup times (now my clicky is preloaded for Ztilt en Meshing :) ). however, my klicky sits quite low resulting in a rather large z_offset of 5mm. If I set a safe_z lower then 5mm the bed will move up to far after homing with clicky still attached and ramming the bed into the probe.

A simple fix would be too incorporate the z_offset parameter into the code and adding that into the safe_z in the home z routine.