replwrap style run function

It would also be nice to borrow from replwrap and have a method to fold these three lines into one:

    p.send_line("hostname")?;
    let hostname = p.read_line()?;
    p.wait_for_prompt()?; // go sure `hostname` is really done

becomes something like

    let output = p.run("hostname")?;

other things that would help missing from pexpect that I've had to add for run(): take multiple commands to pass a script that you read from the host filesystem either as a vec or by splitting on newlines, sanitizing carriage returns, stripping out colour

Start by locating the existing send_line, read_line, and wait_for_prompt entry points and compare the requested API with replwrap's run behavior. Define what a returned output should contain and how multiple commands, carriage returns, and color stripping are handled; done means a run-style method covers the shown hostname flow and the listed script inputs.