remove duplicate test coverage with t/hash.t
fix test count
small code reorganization

* DeepEqual makes deep_equal be in @EXPORT
* DataDriven layout emphasizes run_where()
added wiretap. Fixed short-circuit in DeepEqual::_same_hashrefs

Previously in _same_hashrefs() I'd written:

   foreach my $key (keys %$exp) {
      next unless exists $exp->{$key};   # XXX should be $got->{key}
      return 0 unless deep_equal($got->{$key}, $exp->{key});
   }

Added a test to t/hash.t to catch this, which required that I add a
wiretap. (It's pretty light-weight.)
mv Test::Easy::utils::tester -> T:E:equivalence