Log Message:
Update p5-Test-Differences to 0.61.

Changes from previous:
0.61 Sat April 16, 2011
    - Allow an option to override Sortkeys in C<eq_or_diff>. Thanks to Mark
      Zealey for the suggestion.
    - Unnumbered tests. There's no point to them.

0.60 Sat April 16, 2011
    - Make '' and undef not equal. Thanks to Pavel Shaydo for the patch.
    - Made Data::Dumper minimum version 2.126 to resolve
      https://rt.cpan.org/Ticket/Display.html?id=60798. Thanks to
      jjnapiork@cpan.org  for the report and fix.