> I wish there was some reasonable standard (like a better version of Rich Text) that was commonly adopted so other languages could put graphical pictures in the source code.

I have felt exactly the same for many years. It would need to be something that was totally open (to achieve wide adoption), and reasonably easy to support in IDE's for edit and preview. And git-friendly. Belly-flopping on an existing standard is probably the easiest way to make that happen.

One thought is to presume a block comment with a language-specific marker, and make the contents a restricted subset of Postscript. a) You get one or two open-source fonts. Deal with it. b) The rendering area is strictly limited, c) the operator subset is limited to something reasonable -- like just enough to do a monochrome version of 80% of the kind of graphics that PowerPoint-ish programs give you.

Of course, you would never want to write Postscript by hand (although it isn't hard) but an IDE should be able to support a graphical editor plug-in. Or in a pinch you could even use another tool that left the rest of the code alone, and just edited the graphical block comments.