LT-22038: Tone diacritics are hardly visible

[jtmaxwell3]

I fixed https://jira.sil.org/browse/LT-22038 by stripping dotted circle characters from a project when converting the project into a Hermit Crab or XAmple grammar. This means that users can use the dotted circle character to make standalone tone diacritics easier to read if they want (as suggested by Andy Black).

This is for release/9.3.

---

This change is