(See #11 why this is needed)

The MarkdownSharp parser is fatally flawed: the html paragraph finder uses a regex that is broken, yet it's very long/complex. This makes it skip html block elements it should hash/escape otherwise and wraps them in paragraph tags, causing flawed HTML output.

MarkdownDeep is another markdown parser and we'll move to that. This has consequences: the extensions used by DocNet have to be ported as well.