Cabal revisions of free-3.0

Hackage metadata revisions edit the .cabal file after upload; each diff below is one revision.

 name:          free category:      Control, Monads version:       3.0+x-revision: 1 license:       BSD3 cabal-version: >= 1.6 license-file:  LICENSE     UndecidableInstances    build-depends:-    base                 >= 4       && < 5,+    base                 >= 4       && < 4.7,     distributive         >= 0.2.1   && < 0.3,     transformers         >= 0.2.0   && < 0.4,     mtl                  >= 2.0.1.0 && < 2.2,