Fix behavior of List#groupWhen and groupWhenM. Change return type to List[NonEmptyList[A]]. Add tests which are somewhat pointless until better arbitrary[(A, B) => C] can be implemented
Use greek letters for type lambda per contributor guide
Make behavior of IndexedSeq#groupWhen and groupWhenM match List#groupWhen and groupWhenM
Merge pull request #707 from drstevens/FixListGroupBehaviorTests

Fix behavior of List#groupWhen and groupWhenM.