Merge pull request #5 from DavidNicholls/cam-py

Merged Andrew's cam-py branch with my latest changes.
Merge branch 'cam-py' of https://github.com/andrewjrobinson/FreeCAD_sf_master into cam-py
Merge branch 'nightly' into cam-py
Merge pull request #6 from DavidNicholls/cam-py

Thanks David.  All implemented features tested ok under Linux