Convert CodingDojo.org from UseMod WIKI to Markdown

[al-the-x]

First steps as discussed with @egaillot regarding CodingDojo.org is to convert the existing UserMod-based WIKI into Markdown for use in a Jekyll- or Gollum-based site hosted by Github pages.

[al-the-x]

Found scrape-markdown on npmjs.org that takes HTML, optionally with a CSS-style selector as an element filter, and produces Markdown files. I also found Text::WikiConverter in CPAN that does similar but seems harder to use by comparison.