mpmath.org, documentation and codecov integration

[Sergey B Kirpichev]

Hello,

it seems, the mpmath documentation for git version is not up
to date. See e.g. https://github.com/mpmath/mpmath/issues/644

Could we solve this little problem, Fredrik?

So far I created the mpmath project on the RTFD:
https://mpmath.readthedocs.io/
I think this is a good option to host the mpmath docs.

This project has pdf and html docs for the git version
and for the latest stable release (v1.3.0), just as mpmath.org.
So far, the docs here require a manual intervention to trigger
a build. But we can automate this:
https://docs.readthedocs.io/en/stable/guides/setup/git-repo-manual.html
This will enable also documentation builds for pr's. (You can
see how it looks e.g. here: https://github.com/diofant/diofant/pull/877)
You also can use subdomains for docs:
https://docs.readthedocs.io/en/stable/guides/custom-domains.html

I can add you as a co-maintainer for this project, if you have a RTFD account.

The mpmath.org has other minor issues, e.g. source code, issues,
"fork me" and so on --- all point to the old github project.

Slighly unrelated (but an important) issue is the codecov.io
integration. Now https://app.codecov.io/gh/mpmath/mpmath is
up to date and shows coverage status for open prs. But I think
it could be much more useful if this information will be available
among other pr checks. Again, see an example:
https://github.com/diofant/diofant/pull/877
Probably, you can consider adding the codecov.io integration:
https://docs.codecov.com/docs/github-2-getting-a-codecov-account-and-uploading-coverage#install-the-github-app-integration