Transformed existing content to use the shorthand Blockdown format whenever possible. Related to builder#103.

Updated all existing content with link to the Ethical Design Manifesto. Progress towards themes#111.

Updated prevalence template tags so that they’re on their own lines so the markdown parser doesn’t choke on them.

Manually massaged the prevalence sections so that they’re no longer lists but paragraphs. Progress towards #163 (there are some open merge requests which use the old template which will need updating after merging into master.

Reorganised the files into /sites and /trackers. Removed the old simple tests. Started updating the format.