Restructure Kino.SSH API

[jannikbecher]

I looked into sshex to get some ideas.

KinoSSH works like this:

Kino.SSH.connect()

renders a new xterm, starts a connections and opens a channel with pty

Kino.SSH.open_channel()/close_channel()

openes a new channel to communicate with the open connection

Kino.SSH.run()

runs a command inside the specific channel
doesn't wait for a response

Kino.SSH.cmd!()

waits for the response

Kino.SSH.stream()

listens for ssh data. Can be consumed by Kino.listen()