Changes to IK for trajectories

[petercorke]

IK methods return a named tuple that holds joint coordinates, success, reason for failure, residual, number of iterations.

For a trajectory used to return a list of these tuples, but that meant quite a bit of work to get the joint angle trajectory which is a common use case.

Now, only a single tuple is returned, but the elements represent a trajectory:

• joint coordinates are a 2D array, one row per time step
• other elements are either a 1D array (numeric or bool values) or a list