Pack Circles

This is an OpenSCAD module to be included in other projects. It generates circles, packed tightly into a larger circle. I built this to create a battery case in OpenSCAD, and hopefully it's useful to someone else.

Packing here is suboptimal for 8 or more circles, because my circles are equidistantly distributed, so optimisations based on non-symmetric distributions aren't made.
Ring spacing is done by the TLAR optical method, to a couple of decimal places...
Some circles in some arrangemen