Stable Drupal 6 release for I18n_Boxes

Currently the Drupal 6 branch exists solely in git, with a near 1-to-1 port of Benclark's original code (various files/functions were renamed to add the underscore in i18n_boxes) but no official release. Ben mentioned he'd be willing to co-maintain the D6 branch here, and I've added him as a co-maintainer. This issue serves as a placeholder for any issues or questions that may pop-up backporting our changes from master (7.x-1.x).

Many of the changes are simple code formatting fixes for D7, while others deal with module name changes in i18n sub-modules. There are also a few bug fixes, and we added ctools caching, as well as some fixes dealing with the string refreshing functionality. Sadly, neither I nor Pablo (citlacom) are at a point were we can take time to test internationalization integration in Drupal 6 anymore. We currently have the Drupal 7 version of this code working out in the wild on two sites.

If you feel comfortable with the fixes (and preferably have a site using the code ;) and are willing to maintain it, we can cut a release for D6, otherwise, I would prefer not to make a stable or recommended release for Drupal 6.