autocomplete commands

[maxlath]

add the possibility to autocomplete properties and values from text input

clues:

• cli-autocomplete
• terminal-kit has an autocomplete feature

[fuddl]

1. when you type wd claims (or any other command that expects a Wikidata-Entity) and
2. The next parameter is not a Wikidata-Entity (it doesn't match /^Q\d+$/)
3. hitting tab should propose label and description that match the entered string (like wd search Ligo)
4. it should then be possible to select an entity using the ↓ and ↑ keys