* Shell
** Add faces instead of reusing font-lock-{comment,string}.
** Understand ~autocd~ and ~cd !$~.
** Use Bash completions.
E.g. in most terminals, typing ~ls TAB~ in a folder with a single file
expands to ~ls that-file~.
* Eshell
** ~ls --group-directories-first~ does not color folders.
* Python shell
** Handle ~completion-prefix-display-length~
Setting this variable in an inputrc file causes the Python interpreter
to elide common prefixes when showing completion candidates.  This
seems to confuse python-shell-completion-native-get-completions (at
best hitting TAB yields "No match", at worst it makes Emacs hang).