temp implementation of indtosub based on numpy unravel_index
add ordering info to indtosub test
working row-major indexing without numpy
add nonfunctional 'one-based' param to indtosub and tests
working zero-based indtosub
temp impl of subtoind based on ravel_multi_index; change in behavior outside of range from original
add numpy-based row-major ordering test to subtoind
working row-major subtoind
working zero-based subtoind