functions in Dim2Search simplified and comment added

renamed unionWithConv to unionMapWith, some refactorization

cabal file refactored: dependency form data-size in conditional compi…

…lation, default off

this enables easier test of strictness properties

generalized union "unionWithConv" added

changes to work with data-size-0.1.3

foldl and foldr reexported in Stringmap.Strict

instance of Traversable added to StringMap

foldl and foldlWithKey added

fold and foldWithKey depricated, foldr and foldrWithKey added

cabal test: all tests pass