Known issues with the [[plugins/comments]] plugin:

* There is some common code cargo-culted from other plugins (notably inline and editpage) which
  should probably be shared
* Previews always say "unknown IP address"
* Add `COMMENTOPENID`: the authenticated/verified user name, if and only if it was an OpenID
* The default template should have a (?) icon next to unauthenticated users (with the IP address
  as title) and an OpenID icon next to OpenIDs