Module nvectorBase

(INTERNAL) Private elliposiodal and spherical Nvector base classes LatLonNvectorBase and NvectorBase and function sumOf.

Pure Python implementation of n-vector-based geodesy tools for ellipsoidal earth models, transcoded from JavaScript originals by (C) Chris Veness 2005-2016 and published under the same MIT Licence**, see Vector-based geodesy.