[mfg-smartcam] Thread milling

[Bill Payter]

We've had this discussion before, SmartCAM WILL output offset code for helical milling but will not show it correctly in show path or show cut.   Create, with no offset, your helix, an arc and a line lead-in and out, (manually, not using geo-edit).   Group the arcs and the helix and property change to offset.   This works, check the code.