Support interactive commands

[dotterian]

When I try to add commitizen to prepare-commit-msg hook I encounter following problem: Commitizen is interactive program awaiting input from user into stdin and Lefthook uses pty which doesn't support passing stdin.

Is there any real reason to use pty instead of exec.Command? (found this solution here) Anyway, it would be great to have interactive option to specify that executing hook should get stdin. Also, interactive shouldn't be mixed with parallel, since there can't be several simultaneous interactive processes in one cli.

Alas, I don't know Go and can't write Pull Request myself.