Model rigid body tree motion given joint-space inputs

The `jointSpaceMotionModel`

object models the closed-loop
joint-space motion of a manipulator robot, specified as a `rigidBodyTree`

object. The motion model behavior is defined by the MotionType
property.

creates a motion model for a default two-joint manipulator.`motionModel`

= jointSpaceMotionModel

creates a motion model for the specified `motionModel`

= jointSpaceMotionModel("RigidBodyTree",tree)`rigidBodyTree`

object.

sets additional properties specified as name-value pairs. You can specify multiple
properties in any order.`motionModel`

= jointSpaceMotionControlModel(Name,Value)

`derivative` | Time derivative of manipulator model states |

`updateErrorDynamicsFromStep` | Update values of `NaturalFrequency` and
`DampingRatio` properties given desired step response |

[1] Craig, John J.
*Introduction to Robotics: Mechanics and Control*. Upper Saddle River,
NJ: Pearson Education, 2005.

[2] Spong, Mark W., Seth Hutchinson,
and Mathukumalli Vidyasagar. *Robot Modeling and Control*. Hoboken, NJ:
Wiley, 2006.