[development] Move all core modules into their own directories.

We've discussed this to death during the freeze (even though we weren't supposed to), and most (if not all) the developers feel this is a good idea. When can we get around to doing this. The biggest issue I see is that all patches for 4.7 won't apply on HEAD. That is inevitable anyway, so I think we should just go for it already. =) -- Adrian Rossouw Drupal developer and Bryght Guy http://drupal.org | http://bryght.com