Add some features to make the program more usable.

New Features

Extended search function: Otter-launcher now search for not only module prefixes, but also module descriptions. So if you search fzf, all fzf related stuff will be shown and can be selected with arrow keys. This give practical use to otter-launcher's list selection mode.
Undo auto-completion: Hit tab again to undo auto-completion. This gives vi mode user a simpler way to undo completion instead of hitting 'esc, u'.
Completion now comes with a space after the inserted text, so that users can start typing arguments immediately instead of hitting space again before typing.

Other

Have figured out a hacky way to render chafa image to the left of the selection list, which is done by putting ascii codes into interface.list_prefix. Check readme and helper scripts. I'm still wondering whether should I integrate image presentation as a built-in feature or not.

Quickfix for the enter key misbehaving when selecting list items
Quickfix for weird enter key behavior
Fix item selection not working when interface.suggestionlines is equal to module counts