Allow complex identifiers in @memoize_in

See merge request !43

Fix a README typo

mo(n)keypatch :-)

setup.py: Drop 3.4, 3.5 support

`__init__.py` uses PEP 526 variable annotations, which are supported only in 3.6+

Work around numpy/numpy#16564 in make_obj_array

See merge request !42

Fixes to obj_array.py

1) Fix a typo
2) Rename decorator for consistency with others

Obj array revamp

See merge request !41

Keyed memoize

See merge request !40

Deprecate indices_in_shape

See merge request !39

Bump version

Mypy support + PEP 561 support