Basic Customizable Gear - true diameter

The original SCAD file interprets the diameters as a radii, and does not accept fractional diameters, so odd diameters are impossible. With this minor fix they are now possible!

The v2 version corrects a cog length issue.

Note there was a Customizer problem within Thingiverse before; if you still have trouble it can be worked around by installing OpenSCAD and running Customizer locally, using the instructions here:

- Download the latest version of OpenSCAD (which includes Customizer)