Move make_unique to its own header
Add newton meters to units.
Add function to set spindle torque.
Update tests to not specify gcode variant.
Add constructors to specify units directly.
Add function to build axis from type.
Validate axes for rapid and feed rate configuration
Implement machine configuration object.
Implement test for new configuration object.
Merge branch 'master' of github.com:mythagel/cxxcam