`extraBinPackages` was not passed from the home-manager module to the
derivation. Thanks to @he-la for noticing and reporting this.
Group and order the options to hopefully make this easier to spot in the
future.
This should work around #14, which breaks fetches on newer versions of
Nix. I was hesitant to expose this as Nix changes may break things with
no warning, but it gives users already willing to run newer versions of
Nix a workaround for the fetch failures they're currently getting.
(And the feature itself seems to work fine on current Nix, since CI is
using it...)
