Add type annotations to toolz and cytoolz

[hunterhogan]

• __init__.py
• _signatures.py
• functoolz.py
• itertoolz.py
• recipes.py
• utils.py
• curried/__init__.py
• curried/exceptions.py
• curried/operator.py
• sandbox/__init__.py
• sandbox/core.py
• sandbox/parallel.py
• sandbox/tests/test_core.py
• sandbox/tests/test_parallel.py
• tests/test_compatibility.py
• tests/test_curried_doctests.py
• tests/test_curried.py
• tests/test_dicttoolz.py
• tests/test_functoolz.py
• tests/test_inspect_args.py
• tests/test_itertoolz.py
• tests/test_package.py
• tests/test_recipes.py
• tests/test_serialization.py
• tests/test_signatures.py
• tests/test_tlz.py
• tests/test_utils.py

tlz only

• __init__.py
• _build_tlz.py

cytoolz only

• tests/dev_skip_test.py
• tests/test_curried_toolzlike.py
• tests/test_dev_skip_test.py
• tests/test_docstrings.py
• tests/test_doctests.py
• tests/test_embedded_sigs.py
• tests/test_none_safe.py