OpenScad Revoloids version 0.7

Inching closer to perfection.

This thing is an update to the revoloids library.

This time around, I've gotten the normals calculated correctly, so that a 'shell_extrude' can be performed. So, now there are two methods in the revoloids.scad file: linear_extrude_revoloid, shell_extrude_revoloid

The first one will 'intrude' towards the center of rotation. that's a nice valid way of doing things, but the ends must be relatively flat or things will get messed up.

The shell_extrude, which is new here, will 'do the needful' and extrude inward, or outward, based on the normals at the points on the curves (circule, and cubic curve). That's useful in some cases, and you'll get a uniform thickness across the piece.

There's some nice 'visual debug' support, so you can see fancy colors, wireframes, normals, and the like (exhibited in the attached pictures). And yes, it does in fact generate valid .stl files (exhibited in the attached .stl files).

What more can be done with thi