Refactor: "params" in NewlineJoin saves lots of syntax.

I don't know why I didn't think of it when I introduced that function.
NewlineJoin with variable parameters now provides a simple way to generate
expected output strings, multiline commands, scripts, etc. All without much
syntax overhead.
Merge pull request #208 from sburnicki/reference_host_refac

Refactor: "params" in NewlineJoin saves lots of syntax.