Avoid merging dotted notes with different accidentals

[Alexander Myltsev]

Hi,

I'm trying to keep Lilypond from merging the same dotted note with
different accidentals in different voices. My first approach was to
override NoteColumn.force-hshift, which moved one of the notes, but
kept the accidentals together, like this:
♯(♮) ♪♪

I'm trying to pull apart notes together with their respective
accidentals, like this:
♯♪  (♮)♪

My next approach was to override extra-offsets for notes and accidentals:
https://gist.github.com/avm/cf35e1294ee75b65b37225e77149a7e0
This looks almost right, but the augmentation dot is still shared (and
oddly placed).

How do I avoid merging the augmentation dot? Is there a better way to
typeset this?

-- 
AVM