Proposal: Add conspicuously missing Functor instances for tuples

[Henning Thielemann]

On Tue, 19 Jan 2016, Edward Kmett wrote:

> +1 from me. 
> We routinely supply instances for tuples of up to 4 or 5 elements elsewhere. 

There are only liftA2 and liftA3 (supporting only (,) and (,,), 
respectively), how little is this? :-)

I like consistency, too, and thus propose to remove all Functor, Foldable, 
Traversable, Applicative instances from all tuples.