examples/python:  updates line-denisty profile data example
examples/python:  updates line-denisty profile data example

- reflects the updated API names for the space-charge elements
- uses updated/streamlined line-density profile data API

SixTrack/SixTrackLib,SixTrack/SixTrackLib,SixTrack/SixTrackLib,SixTrack/SixTrackLib