Import only used class methods of Foldable.

On GHC 7.8, the Foldable class contains also null and length, which
conflicts with Data.Sequence{null,length}.

Author: foxik

tests/seq-properties.hs

@@ -3,7 +3,7 @@ import Data.Sequence    -- needs to be compiled with -DTESTING for use here
 import Control.Applicative (Applicative(..))
 import Control.Arrow ((***))
 import Data.Array (listArray)
-import Data.Foldable (Foldable(..), toList, all, sum)
+import Data.Foldable (Foldable(foldl, foldl1, foldr, foldr1), toList, all, sum)
 import Data.Functor ((<$>), (<$))
 import Data.Maybe
 import Data.Monoid (Monoid(..))