patch applied (packages/base): add superclasses to Applicative and Traversable

[Ross Paterson]

Tue Apr 11 07:47:34 PDT 2006  Ross Paterson <ross at soi.city.ac.uk>
  * add superclasses to Applicative and Traversable
  
  Functor is now a superclass of Applicative, and Functor and Foldable
  are now superclasses of Traversable.  The new hierarchy makes clear the
  inclusions between the classes, but means more work in defining instances.
  Default definitions are provided to help.

    M ./Control/Applicative.hs -19 +27
    M ./Data/Map.hs -1 +1
    M ./Data/Sequence.hs -2 +14
    M ./Data/Traversable.hs -20 +23
    M ./Data/Tree.hs -1 +1