Minor changes to improve printability on FDM printers. The .scad file uses the experimental roof() module, so you'll need a nightly build of OpenSCAD to use it.

CHANGELOG

• added 45° taper to extrusion (uses experimental roof)
• use alternative underscore character for consistent stroke width
• corrected the orientation of 6 and 9 on d20
• omit dice by setting height to 0 (works better with OpenSCAD customizer)
• improved dice placement