[Feature Request] Allow for TTYs other than STDIN

[upsampled]

Feature Request

Right now it appears like go-prompt only works with STDIN. In order to run it on a console port, I currently use SystemD to perform STDIN redirection and a few other hacks (set windows size etc.). I think I could replace systemd with syscall.Dup2 but I don't have time to experiment much more.

StandardInput=tty
StandardOutput=tty
TTYPath=/dev/...

Anyhow if you can confirm that:

1. there is not nicer way to do this
2. that adding a parameter TTY *os.File parameter to Options would be a good way for go-prompt to accept an external TTY

then I'll work on a PR