Log Message:
Import mediawiki-mode-2.2.4 as wip/mediawiki-mode.

An excerpt from the website:

  I took the mediawiki mode from an old copy on wikipedia.org and
  refactored the code to use internal Emacs url-http libraries. I also
  added customization and a site alist so that you can easily toggle
  between different mediawiki sites. Finally, I added a page ring so
  that by using M-p and M-n in any mediawiki.el buffer, you can go
  forwards and backwards.