Fixed passing struct as argument. We are using solution with both ctypes and cython structs. There will not be a lot additional work when defining cython structs, because we need only say what't the name of struct type, and put elif statement (objc_cy_types.pxi). Details about struct fields is donne via ctypes structure. If I somehow make structure arguments to work withouth cython struct, it will not be a problem to remove added helper objc_cy_types.pxi file, but I'm not shure it they will work without cast to some C (cython) type.