fix operator -- in dereferencing iterator

alib2std/src/extensions/iterator.hpp

@@ -690,7 +690,7 @@ public:
 	 * \return the modified iterator
 	 */
 	dereferencing_iterator < Iterator > & operator -- ( ) {
-		++ m_base;
+		-- m_base;
 		return * this;
 	}
@@ -704,7 +704,7 @@ public:
 	 */
 	dereferencing_iterator < Iterator > operator -- ( int ) {
 		auto tmp = * this;
-		++ m_base;
+		-- m_base;
 		return tmp;
 	}