EnumSet: follow latest containers
EnumSet: rename type variable e to k

This seems closer to the containers' use of Key type synonym.
EnumSet: use (***) instead of helper functions
update copyright notice
EnumSet: minor changes
EnumMap: follow the structure of containers

This introduces Data.EnumMap.{Base,Lazy,Strict}, following the
latest containers.
minor changes (comments, INLINE pragmas)
cabal: update version, modules, etc.