Allow multiple ;-separated commands in run!

[casey]

What do you think about allowing the following:

run!(
  "echo foo";
  "echo bar";
);

I've wanted it a few times, just to make my scripts more compact. It's "macro magic", but I think probably worth it, since I can't think of strong downsides. This would only work for run!, since it's the only macro that doesn't produce output.