Accept authentication through an API key for wiki_backup/* pages
Remove other format links in wiki backup pages (hiding them isn't enough for wget --mirror)
Add explicit '.html' format everywhere to ease wget --mirror
Better link support for wget --mirror, links will now be handled only through <a> tags
Remove useless 'wiki/' part in URLs
Replace wiki links with wiki_backup links when possible (when done through ApplicationHelper#parse_wiki_links especially)
Don't block on non-existing pages...
Add example script for mirroring