endian: add explicit 'native' query for endian::value

endian.hpp

@@ -214,6 +214,8 @@ namespace cruft {
                 return convert<StorageV,scheme::native> (raw);
             }
 
+            ValueT native (void) const { return *this; }
+
             decltype(auto) operator+ () const { return +this->operator ValueT (); }
 
             ValueT operator<< (size_t s) const { return convert<StorageV,scheme::native> (raw) << s; }