setSpeedFactor sets the speed factor that adjusts the speed
of all trajectories.
The speed factor reduces the speed of all trajectories
to the specified multiplier. For example, a speed factor
of 0.5 would turn a 5 second trajectory into a 10 second
This factor gets applied to all trajectories, including
ones that have user specified time.
% double the duration of all trajectories
trajGen = HebiTrajectoryGenerator(kin);
Values above 1.0 are supported, but may result in
trajectories that exceed the joint limits.