An override of the treebeard api in order to send a signal in advance.

def move(self, target, pos=None):
        '''
        An override of the treebeard api in order to send a signal in advance.
        '''
        if self.outline != target.outline:
            raise IntegrityError('Elements must be from the same outline!')
        tree_manipulation.send(
            sender=self.__class__,
            instance=self,
            action='move',
            target_node_type=None,
            target_node=target,
            pos=pos
        )
        return super().move(target, pos)