This in intended to support a coming SDP Swarm installation script that
builds Markdown support into SDP-style Swarm installations. Getting
Markdown to work in Swarm is already straightforward, but there are
enough little (undocumented) gotchas that (getting file/dir perms right,
putting things in the right place within Swarm, etc.) that an installation
script is needed to take it from 'straightforward' to 'easy.'