Make strap test scaffold.
Add thru-holes to increase plastic on rods.
Add internal strengthening in both directions.
Thicken the strap mount in both directions.

Make the strap mount a little wider and a little thicker to improve
the overall strength.
Thicken the strap mounts a little more.
Cleanup strap mount code.

Fix the support-removal code to match the new parameters.
Factor out some calculations and constants so they are not repeated.
Merge branch 'master' into strengthen_strap_mount

Conflicts:
	visor.scad