[opus] celt-dev renamed to opus

[Ralph Giles]

The list migration is complete. Please send new posts to
opus at xiph.org rather than celt-dev at .

Archives are now at http://lists.xiph.org/pipermail/opus/

We've dropped the '-dev' suffix because we don't think it makes sense to
have separate development and user discussion lists.

General Opus codec discussion is on topic for this list, including codec
development, application development using the codec, and general Opus
user support.

Cheers,
 -r