Orange Pi Zero box

This is a remix of the [Compact and Secure Orange Pi Zero Case](https://www.thingiverse.com/thing:1904872) by [ridercz](https://www.thingiverse.com/ridercz) with the following modifications:
* the hole for the antenna has been reinforced with a tube on the inside so the antenna is fixed better to the box;
* the bottom part now has optional screw tabs for mounting the box to e.g. a wall. I've used this feature to mount the box in the fusebox/meter cupboard where it is used to log the gas and electricity consumption in our house;
* the box is generated from an OpenSCAD file that allows for easy configuration. The screw tabs are controlled through a simple selector (a variable that is either 0 or non-zero), the position of the antenna hole is controlled through 2 other variables, etc.

The top box part that can hold the extension board is not part of this remix, but you can combine the bottom part with the screw tabs from this thing with the extension board top part of the original t