MT4 comments: external authentication

Seriously, this time it works! You can try authenticating using LJ, Vox, TypeKey or OpenID for comments, and they are posted automatically (when it goes back to the original page, just refresh to see your own comments).

It turned out that I forgot to refresh my MT's site Javascript, one of the index templates, and consequently the "writeCommenterGreeting()" JS function required to show the "Sign In" link and hide the default anonymous form wasn't present (it was called "writeTypeKeyGreeting" in previous incarnations of MT, allowing only one type of authentication).