We're not using it anymore. Any leftover bugs in the Meson buildsystem
are now just bugs.
Closes#249.
Change-Id: I0465a0c37ae819f94d40e7829f5bff046aa63d73
Allows completing `nix build ~/flake#<Tab>`.
We can implement expansion for `~user` later if needed.
Not using wordexp(3) since that expands way too much.
Make nix output completions in the form `completion\tdescription`.
This can't be used by bash (afaik), but other shells like zsh or fish
can display it along the completion choices