Created node for dynamic scan trajectories

[DavidSpielman]

Created a node that uses a noether toolpath planner to create a configurable snakelike scanning trajectory on a plane of configuarable dimensions. The spacing of the waypoints on this plane is also configurable.

Motion plans are generated from the given toolpaths. Current implementation does not incorporate future expected changes to the GenerateMotionPlan and GenerateScanMotionPlan services.