I don't think diagrams are meant to be copy-pasted from a lot, so I'm not worried about that. For editing, I'd just use a conversion tool, and edit it in a fix

I don't think diagrams are meant to be copy-pasted from a lot, so I'm not worried about that. For editing, I'd just use a conversion tool, and edit it in a fixed-width editor rather than directly in code. Yes, it's an extra tool, but I don't think it's that outlandish to edit pictures in a tool for editing pictures.