Fix bug in date sorting reported by Ben Martin.
Fix bug in domain name sorting that I got on trying to sort the NWJL mailing list.
    Domain names work fine. The problem arises with email addresses.

Case-folding does not preserve normalization, so we should either normalize
after case-folding or, if it is necessary to normalize earlier, renormalize
after case-folding.

Need to update case-folding and transformations to Unicode 5.1.
