Updating CalculatorHistory to use a default destructor. (#723)

Its memory will be cleaned up by std::vector's destructor.

src/CalcManager/CalculatorHistory.h

@@ -43,7 +43,6 @@ namespace CalculationManager
         {
             return m_maxHistorySize;
         }
-        ~CalculatorHistory(void);
 
     private:
         std::vector<std::shared_ptr<HISTORYITEM>> m_historyItems;