Hershey fonts for OpenSCAD

The standard OpenSCAD fonts work well for a simple extrusion 3D profile. But what if you want a different 3D profile, e.g., you want text that looks like it's been machined with a V-shaped bit, or text that is rounded in 3D?

This library includes the ASCII portions of the Hershey vector fonts, and draws text using whatever convex shape you specify. For instance, you can do rounded text via:

use ;
drawHersheyFont("Hello, OpenSCAD!", font="Script") sphere(r=2,$fn=16);

A call to `drawHersheyFont()` requires a child object that specifies what the drawing is done with. The drawing is done by putting the child object at the two endpoint of a lines and doing a `hull()` operation.

The following optional arguments are available:

`halign="left"|"right"|"center"`: horizontal alignment
`valign="top"|"baseline"|"center"|"bottom"`: vertical alignment
`size=x`: specify height of capital T
`extraSpacing=x`: add this extra spacing between letters (can be negative)
`forceMi