Proposal: Bounded instance for IntSet (ticket #1953)

>From http://hackage.haskell.org/trac/ghc/ticket/1953 :

I propose to add a Bounded instance to IntSet.hs.

IntSet is in Ord, and there are only finitely many instances of
IntSet. Therefore there is a min IntSet and a max IntSet. It turns out
these bounds are very simple:

instance Bounded IntSet where
    minBound = empty
    maxBound = singleton maxBound

Suggested deadline: December 16, 2007.