I can't find any editor (outside of emacs) that has a mode for it. And it needs a mode ;-)
In fact, because of the way it's marked, it seems a mode for scintilla or kate simply can't be done.
The problem is that, in order to understand what a paragraph is, you need to see the end of it, sometimes (for example, headings)
So, since most highlight parsers switch when they trip onto something (say, a quote), it doesn't work.
I could, I suppose, do highlighting using something more evil, like detecting when the user ends a paragraph to set the paragraph's style, in addition to the usual stuff, but it seems pretty hard to get right.