Quick fix. The assignment operator for SetIterator.h did not return a value....

Quick fix. The assignment operator for SetIterator.h did not return a value. This didn't cause any known current errors, but g++ 3.4.1 noticed.

os/dijkstra/SetIterator.h

@@ -110,6 +110,7 @@ public:
         secondEnd = right.secondEnd;
         predicate = right.predicate;
         currentSet = right.currentSet;
+        return *this;
     }
 
     void reset(T const & first, T const & second)