Renamed nditer to cython_npyiter
Ignore cython generated cython_npyiter/erfa.c
In cython_numpy, C int are numpy.int32
Implemented d2dtf()
Implemented aper()
Implement atco31()
np.zeros() -> np.empty() (faster)
Also test cython_npyiter
Remove bare ellipsis
op_flags generalisation and cleanup