docs: "API Reference" support added

[mpusz]

This is the framework to present API reference.

We can't proceed with this until the initial version of the API Reference HTML is prepared.

[JohelEGP]

Shouldn't this target the gh-pages branch?
All master should need are the .tex files used to produce the PDF and HTML documents.

[mpusz]

I don't think so. gh-pages content is automatically generated during the documentation build. For now, we do not have tex files that could be generated, so I added htmls instead. However, all the rest of the files besides api/gen subdirectory need to be on the master branch.

[mpusz]

Of course, this is not ready yet as well. For now, I just handle the internal and wg21.links, but your docs also had other URLs. We will have to decide to handle them as well (i.e. open in a separate browser tab).

[JohelEGP]

The big .css file is part of the https://github.com/Eelis/cxxdraft-htmlgen checkout that is downloaded during documentation generation.

The links into https://www.electropedia.org/ could be opened like the internal links.
They are simple webpages and should be nice to view in the frame:
https://www.electropedia.org/iev/iev.nsf/display?openform&ievref=102-01-24.
They also have these simpler hidden links:
https://www.electropedia.org/iev/iev.nsf/17127c61f2426ed8c1257cb5003c9bec/dcaa2ce786340500c1257f9d0037eb24?OpenDocument.

[mpusz]

Sure, we will tune it when we have the first version generated.

I spent lots of time in finding the best way to display standardeese-like pages inside the mkdocs framework with the original styling. But I am quite happy with the result. But of course, it is not perfect and if someone knows web programming better than me, please let me know what can be improved.