spew_lines with test

This PR creates a new method called `spew_lines` - it's just like `spew`, but if a plain scalar is passed, it appends $/ to that scalar. Otherwise, if an array ref is passed, appends $/ to each element of the array.

If `spew` is the opposite of `slurp`, `spew_lines` would be the opposite of `slurp( chomp => 1 )`

Documentation and a test are included.