Parametric Footplate - Square Grid Pattern

I have used footplates on a number of my [projects](https://www.thingiverse.com/thing:2690349). These were all made by hand and tended to be a bit tedious to reconfigure for different sizes. So I decided to create a parametric version for hexagonally packed openings which I uploaded [here](https://www.thingiverse.com/thing:3150685). It was a very simple job to adapt this to a square grid pattern which is presented here.

The OpenSCAD model does not include any safeguards for restricting the