Interlocking Card Tray - v2

As this model deviates further from the original, I thought I'd release a v2 of it to keep things separate.

Changes from the original model include a configurable horizontal and vertical interlock system. I'll tweak this one eventually to allow a configurable finger access dimension, but for me these trays already work pretty well now.

The top/bottom interlocking let's you stack the trays when not in use. If you print one and stop the print process at 2mm, you will get a piece to fit on top. You can then wrap some elastic bands round the interlock system to keep everything together when not in use.

I've tried to comment the code well to both help me maintain it, give beginners some insight into how it works, and let other experienced coders snatch any part they want. I should also attribute the fillet formala used, which I didn't write. I think I got it from an OpenSCAD forum.