Proposal: move (group|sort)With to Data.List

[amindfv at gmail.com]

GHC.Exts contains a couple of really useful functions:

groupWith :: (Ord b) => (a -> b) -> [a] -> [[a]]
sortWith :: (a -> b) -> [a] -> [a]

There seems to be no reason why they wouldn't be -- more sensibly -- in Data.List. I propose we move them (and "the" while we're at it).

Tom