Bash and zsh completions

Let's provide bash and zsh completion definitions. Maybe fish, too? They're out there in some other packages. Maybe we could pull those in. ### bash [Fedora's cowsay package](https://packages.fedoraproject.org/pkgs/cowsay/cowsay/) has bash completion definitions, in a source file ([cowsay.bashcomp](https://src.fedoraproject.org/rpms/cowsay/blob/rawhide/f/cowsay.bashcomp)) local to the RPM package spec, licensed under GPL v2. Looks like they were in turn pulled in from Gentoo. ### zsh _Something_ seems to be supplying zsh completions for cowsay on my Mac. When I do `cowsay -f x<TAB>`, it completes the unqualified cow name from the set of installed cows. Don't know what's supplying that. I have the Homebrew `zsh-completions` package installed, but I don't see cowsay completions there. I see this in my shell: ``` $ which _cowsay _cowsay () { local context state line typeset -A opt_args _arguments -s -S -A "-*" "(H mode)-e+[specify cow's eyes]:eye string [oo]" '(H)-f+[specify cowfile]:cowfile:->cowfile' "(H mode)-T+[specify cow's tongue]:tongue string" '(H)-W+[specify width for message word wrap]:wrap column [40]' '(H)-n[no wordwrap]' '*:message' + 'H' '(- *)-h[display usage information]' '(- *)-l[list all cowfiles]' + '(mode)' '(H -e -T)-b[borg mode]' '(H -e -T)-d[dead mode]' '(H -e -T)-g[greedy mode]' '(H -e -T)-p[paranoia mode]' '(H -e -T)-s[stoned mode]' '(H -e -T)-t[tired mode]' '(H -e -T)-w[wired mode]' '(H -e -T)-y[youthful mode]' && return case "$state" in (cowfile) _wanted -C option-f-1 cowfiles expl 'cow file' compadd ${=${(f)"$(_call_program cowfiles $words[1] -l)"}:#*\:} || _files -g "*.cow(-.)" ;; esac } $ locate _cowsay /usr/local/Cellar/zsh/5.9/share/zsh/functions/_cowsay /usr/local/share/zsh/functions/_cowsay /usr/share/zsh/5.9/functions/_cowsay ``` Does that mean that _zsh itself_ supplies cowsay completions? Sure looks like it. We still might want to supply our own zsh completions, to support changes to the `cowsay` interface that have happened since the zsh release.