Napier Bones

This thing is inspired on https://www.thingiverse.com/thing:577834
It used the same tables, but the remainder of the code is re-implemented.
The main differences are:
- smaller, so faster printing,
- using an actual font instead of recreating number characters,
- embossed numbers, which work somewhat better for vertical 3D printing,
- less magic values in code and better parameterization, so scaling should be better,
- the bone number is printed on top, making them more easy to identify.

This file can generate STL files for all ten bones, just uncomment the bone-function you want.

I found printing with a 0.4mm nozzle and 0.20mm layer height acceptable, but smaller sizes will improve the quality.
More optimization of the code is possible, but optimization of the result is more interesting.
The txtHeight parameter, which is actually the depth of the numbers, probably works best if it is close to the actual trace-width, or nozzle aperture.
The separators are not very pro