There are a handful of places where we need to strip markup from a piece
of dtext, primarily in <meta> description tags in the wiki. Currently
the dtext parser handles this by having a special mode where it parses
the text but doesn't output html tags. Here we refactor to instead parse
the text normally then strip out the html tags after the fact.
This is more flexible and allows us to simplify a lot of things in the
dtext parser. This also produces more readable output than before in
certain cases.
08b1c76533