Saves internal values to be loaded later

        :returns: dict -- {'parametername': value, ...}

def stateDict(self):
        """Saves internal values to be loaded later

        :returns: dict -- {'parametername': value, ...}
        """
        state = {
                'duration' : self._duration,
                'intensity' : self._intensity,
                'risefall' : self._risefall,
                'stim_type' : self.name
                }
        return state