Add markdownify

[victorbnl]

It would be great to add the markdownify filter

[pwwang]

Could you attach a reference link?

[victorbnl]

Oh, I though you already knew it, as there is a comment like TODO: markdownify, ... in your code (if I remember well). Anyway, the documentation is really concise about it, so I can't tell you a lot of things, apart from the fact it's a Jekyll filter that transforms its input from markdown into html.

Here is the source code of the filter in Jekyll if it can help you: https://github.com/jekyll/jekyll/blob/9957e21be7f45e791725a9e0a963b329f79c2615/lib/jekyll/filters.rb#L16

[victorbnl]

I just saw your code and it doesn't seem complicated, so I'll make a PR

[victorbnl]

Should I include it in the standard mode?

[pwwang]

Ah, then I think it's better to add it to the jekyll mode to avoid confusion. PRs are very welcome, just remember to push to the dev branch.