Style changes when upgrading to Sphinx 4.1

[laurensvalk]

A few things appear to have changed with v4.1. One noticable difference is that v3.X has method names in black, and arguments in gray. In v4 everything is just gray, which is slightly less readable.

Old (left), new (right)

[laurensvalk]

Similarly, functions are now all blue, with the old style being clearer:

Old (left), new (right)

[dlech]

Upstream is working on it: readthedocs/sphinx_rtd_theme#1123

[laurensvalk]

Meanwhile, the other blocking hacks have been removed, so we can upgrade once the aforementioned style issues are fixed upstream.

[laurensvalk]

Upstream has committed a fix. Although not released yet, I might go ahead and pull this to considerably simplify work in #72.

It looks okay now. This is built with Sphinx 4.1 and the latest rtd theme.

One new minor change seems that literals may now break to a new line, but this is something we can look at another time.