This allows Unit<> and AxisUnit<> to be scaled with a fraction as
expected, promoting the scaler to the same unit:
0.2_mm * 10 => 2_mm (mm*f => mm)
Multiplication type is commutative:
10 * 0.2_mm => 2_mm (f*mm => mm)
Division isn't:
0.2_mm / 10 => 0.02_mm (mm*1/f => mm)
10 / 0.2_mm => error (illegal type conversion)
- Move unit/step conversion to modules/axisunit.h
- Unify motion::unitToAxisUnit<> and motion::unitToSteps<>,
making conversion in other modules just as easy as motion.
- Improve the documentation