PEP-8
Implement variadic comp

Generalizes the old PR, against the old functoolz, to provide any
arity to `comp`.
Add docstring and more tests for comp
style changes in comp
change comp tests

remove groupby link

Add tests to cover multiple inputs and keyword arguments
Slightly clarify docstring for comp
Merge pull request #10 from eigenhombre/multiple-arity-comp

Multiple arity comp