Data.IntMap.findMax is missing

[Christian Maeder]

recently I've switched from "Data.Map.Map Int" to "Data.IntMap.IntMap",
but I was disappointed because I did not find a function that would
yield the maximum key faster than in linear time, i.e. O(log n).

In fact the whole "Min/Max" section is missing in Data.IntMap (resp.
Data.IntSet) compared to Data.Map (resp. Data.Set). (The section
"Indexed" is also only in Data.Map.)

Would somebody care to fix this?

Cheers Christian