Make empty text nodes generate newline

[ahmetsait]

A little bit of band aid fix for being unable to use empty text nodes | to introduce spacing.

[schveiguy]

1. dscanner.ini should not be part of this, make it a separate PR.
2. I'm not familiar too much with the parser, but I don't see how this adds newlines for | nodes?
3. Needs a test.

[ahmetsait]

Hopefully @s-ludwig can find some time to review this. Currently it is rather hard to introduce spacing in diet.

[s-ludwig]

Makes sense to go this way. The fact that pug.js has moved to always removing whitespace leaves the question whether there is a good way of following that, or if we simply have to stay on course with the explicit whitespace removal. In any case, this change isn't going to hurt, since pug.js does the same thing with empty pipe text.