[Feature request] Add autocomplete to bash and zsh

[rluvaton]

Thank you for your great work!

It would be so useful if there was an autocomplete for bash and zsh

[diegoe]

I got curious, and I checked how taskwarrior does its completion. Some notes on what ultralist would need:

• ultralist context/tags/projects command, to programatically list existing elements and offer them on + or @ completion
• ultralist commands command to programmatically list available commands and avoid the manual duplication

Long options and etc are more or less a manual affair. git is a good example of completions: https://github.com/git/git/blob/master/contrib/completion/git-completion.bash