Raspberry Pi Zero model

I've heavily revised this thing.
- Rewritten the code now that I understand vector variable types better.
- Corrected the number of GPIO pins (now 20, was 21 )
- Added zeros 1.3, W & WH. Code will be a little easier to maintain too when the next zero model gets announced.
- "ACT" LED now shown (should you need it for a case cutout).
- Option to show GPIO pins colour coded.

- External connectors remains on the "to do" list.

An OpenSCAD model of the Raspberry Pi Zero that I've made to test some print models I'm working on.

Feel free to include this in projects you're playing with (possibly as a check model for cases...). I'd appreciate a message if you find it useful.

If you're using OpenSCAD then you need to use
"PiZeroBody();"
The dimensions I've used are from direct measurement, use the "include" statement if you want to use them in your own project, otherwise its "use".