Update to 1.900

Upstream changes:
1.900    2013-08-08 14:44:43 America/New_York
          avoid trying to stringify undef, and so avoid a warning (thanks, Alex
          Vandiver)

1.899    2013-08-02 10:53:19 America/New_York
          repackaged, pointed at new bugtracker

          fallback overloads are enabled, so "cmp" will now compare with string
          overloads... which still might not be what you expect

          code has been futzed with to rely on some 5.6-isms, rather than
          trying to be 5.005 compatible

          a warning has been added: calling ->parse in scalar context gets
          undefined behavior

1.898    2013-02-07
          remove dead link

(wen)