moving Foldable and Traversable to Prelude

[Henning Thielemann]

On Sun, 19 May 2013, Carter Schonwald wrote:

> +1 on that functor monad bit

Can you please change the subject when you start a new discussion? It will 
be really hard to follow later. The discussion started with whenJust and 
now we are at the third or fourth proposal, depending on whether you count 
Ian's comment as an individual proposal.