add comparison operators between ::_enumerated types & Enum types.

[Auliyaa]

This change allows for comparison between an ::_enumerated type and the Enum type:

BETTER_ENUM(Foo, int, value_a, value_b)

int main()
{
  Foo::_enumerated f1 = Foo::value_a;
  Foo f2 = Foo::value_b;

  if (f1 == f2)
  {
    std::cout << "equal" << std::endl;
  }
  else
  {
    std::cout << "not equal" << std::endl;
  }

  return 0;
}