Update pandoc

[jgm]

If you update the pandoc version you're using, you'll be able to get by with less surgery on the pandoc code base. We've been working on removing C dependencies. Previously, the code syntax highlighting relied on pcre, but I've rewritten it to use a custom Haskell regex engine. We've also moved from the yaml library to the pure Haskell HsYaml (for now anyway*), and we've removed our dependency on cmark-gfm in favor of the pure Haskell commonmark-hs.

It would be really interesting to see if full pandoc can now be compiled with ghcjs.
See jgm/pandoc#4535 which tracks progress in removing C dependencies.

[ozanmakes]

Really cool developments! I will give this a go in the coming weeks.