Rewrite string comparisons with Unicode::Collate

From http://stackoverflow.com/questions/6162484/why-does-modern-perl-avoid-utf-8-by-default/#6163129:

String comparisons in Perl using eq, ne, lc, cmp, sort, &c&cc are always wrong. So instead of `@a = sort @b`, you need `@a = Unicode::Collate->new->sort(@b)`. Might as well add that to your export `PERL5OPTS=-MUnicode::Collate`. You can cache the key for binary comparisons.
