NamedType increment and decrement bypass range checks

[tomjnixon]

this test passes, and probably shouldn't:

TEST_CASE("NamedType_increment_check") {
  using namespace adm;
  using NamedIntegerRange = detail::NamedType<int, struct NamedIntegerRangeTag,
                                              detail::RangeValidator<0, 10> >;
  NamedIntegerRange value(0);
  value--;
}