3 - Maintain several concurrent completion lists,
4 with easy switch back and forth.
6 - Keybinding to switch between completion lists.
8 - File-based completion list.
10 - Better history control
16 - Paren-matching settable despite .inputrc
18 - Hidden characters. (Password-style)
20 - Lightweight version based on alternate library with
21 more permissive license.
23 - Smarter installation