Add InvariantFunctor (from Scalaz 6)
Merge pull request #353 from folone/scalaz-seven

Ported ST and Writer examples.
maximumOf/By and maximumOf1/By1 methods for Foldable(1), plus Foldable(1)Test
tuned
Running a free monad in another monad.
Handy for turning trampolines into futures.
tests for `MinVal` and `MaxVal` semigroups

Contributed in #356 by @oxbowlakes
Merge pull request #354
fix Index[List] and Index[IndexedSeq]
`nil`: smart constructor for `Nil` (similar to `none` for `None`)
Show[java.lang.Throwable]
Added groupBy1 and renamed groupByM to groupWhenM
Re-added groupByM with deprecation message
Added ability to "filter" validations based on the result of a partial function
tuned
Merge pull request #360
Added fold(Right/Left)1Opt and fold(r/l)1Opt
tuned: shorter implementation of `foldMap1Opt`, better tests
Merge pull request #362
Merge pull request #361 from oxbowlakes/groupBy1

Added groupBy1 and renamed groupByM to groupWhenM
Adds mapM to StreamT

mapM threads a per-element monadic effect through the stream