Add splitTree to Map.Base.  Not exposed publically yet.
Change the split method to return a list, as per the discussion on the list.
Bump version number to 0.5.3.2 to reflect change.
Rename to splitRoot.  Add the same for Sets and expose it.
Add splitRoot examples to comments.
Switch to in-order splitRoot.  Provide the same for IntSet/IntMap.
Disable apparently rotted test cases.  10/10 test suites pass.
Add test properties for splitRoot.
Remove the ordering guarantee for IntSet and IntMap.
(Negative numbers screw it up.)
Merge pull request #35 from rrnewton/splittable

Add splitRoot function for Map, Set, IntMap, IntSet.
Fix and reinstate the recently commented tests.

The not working tests were using the join function which we renamed to
link because of Applicative being introduced to Prelude. Nevertheless,
I forgot to update the tests. Fixing now.
Documentation improvements, whitespace cleaning.
Reinstate the ordering guarantees for Int{Set.Map}.splitRoot.
Add traverseWithKey_ variant.