Added UntimeTrajectory() to strip timing from trajectories.
Added UntimeTrajectory() to strip timing from trajectories.

The prpy.util.UntimeTrajectory() function removes the `deltatime`
group from timed trajectories, effectively making them paths.

This is useful for situations in which the trajectory timing is no
longer correct as a result of an inplace transformation, such as
the result of a spatial warping function.

Stefanos19/prpy,personalrobotics/prpy