Fix efficiency claim for zipWith.
Merge pull request #101 from treeowl/zipdocfix

Fix efficiency claim for zipWith.
Fix Arbitrary instance for FingerTree

The previous version never generated deep trees containing Empty.
Also tweaked the size handling so that the tree size is closer to the
specified size (though it can still run over a bit).
Merge pull request #108 from RossPaterson/master

Fix Arbitrary instance for FingerTree
Add tests for Applicative and Monad instances

Unfortunately, these tests are rather slow, so I hid them behind
a SLOW_TESTS macro. I don't know nearly enough about cabal to know
how to arrange for tests to be run conditionally, so hopefully
someone else can set that up properly.
Remove CPP