Sets the endiing date time for this gantt chart.
        
        :param      dtime | <QDateTime>

def setDateTimeEnd(self, dtime):
        """
        Sets the endiing date time for this gantt chart.
        
        :param      dtime | <QDateTime>
        """
        self._dateEnd = dtime.date()
        self._timeEnd = dtime.time()
        self._allDay = False