Fix MLSPosesSmoothing

MLSPosesSmoothing filter was updating the points and arrays of its input polydata. This can lead to segfault if the input it is trying to modify is also updated somewhere else (e.g. if it is the output of another filter). From now, the input PolyData is not modified anymore.

This also adds the smoothed orientation to the output. Until now, it was only added to the input.

Rename KernelSize parameter to KernelRadius, as it implies a more explicit behavior.

Cleaning code.

@nick.laurenson @melanie.carriere @jerome.dias @lea.vauchier PTAL