Parametric socket wrench (mm)

I really liked the design from https://www.thingiverse.com/thing:6747464 , but I needed other sizes as well.
While at it, I also like to have the size of the wrench written on it so that I don't have to guess or measure it.

This remix addresses exactly that.
The model is imported in OpenSCAD, and:
- made parametric to make it possible to print any size. The parametric size is the size of the head of the screw, in millimeters.
- a text part is added to the handle, with the size in millimeters.

A shell script is also present, it makes it possible to (re-)generate multiple sizes in one go.

Note that I'm NOT a seasoned OpenSCAD user, so don't use this file as a reference of best practices.