Magnifying Glass Frame - parametric

I modified the scad file to make it even more parametric.

You can use the Customizer

**Modifications:**
- The handle moves correctly when changing his lenght or the lens diameter
- Added the option to create nuts cavity, or just screw into plastic
- Chamfer on the lens holders to allow to print without supports

**Update 2024-06-02**
- The position of the screw holes is scaled against the handle lenght