QDoc should support the use of en and em dashes in documentation

It would be nice if one could use en dashes and/or em dashes in documentation. Several developers have requested this feature over the years, and to date we haven't received a feature request for it in Jira (at least not that I could find). So this, then, is the feature request.

I would like QDoc to keep up with TeX-like syntax, and treat - and - (two and three hyphens) as markup to generate en dash and em dash, respectively. I would also like QDoc to respect the decrement operator in code, and to not generate a bunch of en or em dashes if I create my own visually striking horizontal rule, e.g. like this: -----.