add nth_list
nth_list indexing from csv
WIP CSV indexing
typo in doctest
get util, nth_list is lazy
add coerce_to_ordered

This should be replaced once DyND nd.as_py supports ordered export
csv produces ordered collections
rec-to-row and row-to-rec are idempotent
json yields tuples
tests use tuples
use get in csv
csv._getitem returns concrete result
replace Files with Concat and Stack
resource uses Stack
add ndget
coerce_to_ordered is idempotent
ordered_index
improve ordered_index
remove debug print
json indexing