Compile fixes on RHEL5/Fedora, see #541

DataStructures/HashTable.h

@@ -36,6 +36,11 @@ public:
 
     HashTable(const unsigned size) : super(size) { }
 
+    HashTable &operator=(const HashTable &other) {
+        super::operator = (other);
+        return *this;
+    }
+
     inline void Add(const keyT& key, const valueT& value){
         super::insert(std::make_pair(key, value));
     }