output always appends a newline

``` haskell
output "test" $ pure "foo"
```

gives a file with `"foo\n"` whereas

``` shell
echo -n "foo" > test
```

gives a file with `"foo"`, `>` doesn’t change the input.

This may be (was actually. :)) source of confusion. Of course it can be migitated by using `Text.writeFile`.