detox is unmaintained and tox has a parallel mode

As per [their blog post of the 27th April](https://blog.readthedocs.com/securing-subdomains/) ‘Securing subdomains’:

> Starting today, Read the Docs will start hosting projects from subdomains on the domain readthedocs.io, instead of on readthedocs.org. This change addresses some security concerns around site cookies while hosting user generated data on the same domain as our dashboard.

Test Plan: Manually visited all the links I’ve modified.

nose-django-querycount gives individual and total query counts. This is
helpful to double-check changes that claim to affect query count
(e.g. #1056).
Total query count gives a quick overview, and diff'ing the output for
two different branches works well.

Faster is better!

When you use the notation with slashes, use full path to file.
With dots, enter module name. Commands run with the current test set.

Test suite time has halved.

They were getting quite long. They've been split up in several
subsections. Some of them are borrowing heavily from the Django docs.