Imporve 3dof simulation code

..._3dof/simple_robot_3dof/forward_kinematics_node_3dof_1.py

..._3dof/simple_robot_3dof/forward_kinematics_node_3dof_2.py

..._3dof/simple_robot_3dof/forward_kinematics_node_3dof_3.py

...ot_3dof/simple_robot_3dof/inverse_kinematics_3dof_node.py