Bash/Zsh bindings for autocomplete

[mafrosis]

It's essential this program is fast and easy to use; autocomplete needs to be added and well tested to make it work nicely. Like git does on zsh.

[mafrosis]

On hold until Click 8 is released:

pallets/click#1622
https://click.palletsprojects.com/en/master/shell-completion/
https://github.com/pallets/click/tree/8.0.0rc1 (released 17 Apr 2021)

[mafrosis]

Click 8.0.1 is released now:

https://click.palletsprojects.com/en/8.0.x/shell-completion/