Allow hintful hunks to not use newline markers

[svenssonaxel]

Implemented on master-syntax2 by fbae4fc, but might be useful on master-syntax1 as well. The use case is using the other features of hintful hunks (snippets and annotations) without having to use newline markers.

[svenssonaxel]

This will make #3 harder to solve, but that might not get solved anyway.