Adding mailto: obfuscation

I've added a plugin that encodes the contents of mailto: links. E.g.: <a href="mailto:lucie.debroux@uni.lu">Lucie Debroux</a> gets automatically translated to: <a href="mailto:%6C%75%63%69%65.%64%65%62%72%6F%75%78@%75%6E%69.%6C%75">Lucie Debroux</a>. @vilem.ded Note, that it does not encode contents of the link (it was not the requirement in our elixir website); if you need it to include contents, let me know