Bugfix: used wrong method to compute a type's tuple set for relations with arity >= 2

git-svn-id: https://cobra.cs.uni-duesseldorf.de/prob/trunk/experimental/plagge/probkodkod@7783 7aec93f6-bc54-0410-ac70-7d7c9efa889a

src/de/stups/probkodkod/types/TupleType.java

@@ -94,7 +94,7 @@ public class TupleType {
 		final TupleFactory factory = universe.factory();
 		final Tuple lowerTuple = factory.tuple(lower);
 		final Tuple upperTuple = factory.tuple(upper);
-		return factory.range(lowerTuple, upperTuple);
+		return factory.area(lowerTuple, upperTuple);
 	}
 
 	/**