add robotics learning grasp contact example

add wsg50 gripper with modified r2d2 gripper tip
expose a fudge factor to scale inertia, to make grasping more stable
(until we have better grasping contact model/implementation)

examples/RoboticsLearning/b3RobotSimAPI.h

@@ -61,7 +61,7 @@ struct b3JointMotorArgs
 		m_targetPosition(0),
 		m_kp(0.1),
 		m_targetVelocity(0),
-		m_kd(0.1),
+		m_kd(0.9),
 		m_maxTorqueValue(1000)
 	{
 	}