Integrate Spivak & Schultz's styling of TikZ wiring diagrams

Spivak and Schultz, possibly with contributions from Fong, have published LaTeX macros at [appliedcategorytheory/TikZWD](https://github.com/appliedcategorytheory/TikZWD) for drawing wiring diagrams in TikZ.

I think their style choices are rather nice. It would be nice to integrate the styling into our TikZ wiring diagrams. David and Brendan have told me that they would be happy to see this happen.

This would be a good first issue for anyone who likes TikZ or is willing to dive into it.