arrays.indexing.rst
updated for None-npnewaxis alias comment
Merge pull request #4621 from jess010/newaxis-doc

update arrays.indexing.rst for 'newaxis' description
Functions for normalizing ufunc.method arguments.
Tests for ufunc.method overrides.
Add ufunc override functionality to ufunc methods `outer` and `at`.
Remove `nin` from PyUfunc_CheckOVerride's signature.
Move declarations as suggested by @charris