As the previous commit explains, it is now possible to specify arguments
to the global options in config files. This means that we can now include
the `exclude-members` option in this global configuration.
Previously, there was no point including this option because it makes no
sense without arguments. Including this option means users have the
flexibility of explicitly including which special methods they want using
(e.g.):
:special-members: __init__, __iter__
or explicitly excluding which special-members (or other members) they want
using (e.g.):
:exclude-members: __weakref__, __hash__