IntSet.findMax generates garbage

Hi, I noticed IntSet.findMax is defined (more or less) as "fst . maxView", but maxView allocates thunks on its way down to the max leaf, only to have findMax throw them away. Same for IntMap. I wrote a patch to fix this. I didn't test it for speed (couldn't think of a good test. I did test for correctness.) However, I looked at the core and the old version did indeed have "let"s in the loop. The new version does not. Also I changed the API a bit. Previously, IntMap.findMin only returned the bound value, not the key. Data.Map returns the pair, so I changed IntMap to do the same. (This seems like common sense to me.) Patch is attached. Can you tell I'm using this library a lot lately? Scott