Move the tree.

        Args:
            delta (tupel): The adjustment of the position.

def move(self, delta):
        """Move the tree.

        Args:
            delta (tupel): The adjustment of the position.
        """
        pos = self.pos
        self.pos = (pos[0]+delta[0], pos[1]+delta[1], pos[2]+delta[0], pos[3]+delta[1])

        # Move all nodes
        for age in self.nodes:
            for node in age:
                node.move(delta)