The links keep the splines to generate the trajectory.
Solved a bug with the computation of the curvature for lanes other than the central one.

Improved Exception report information.
clean_references() functions no longer update references.

Added functions to update the start and end positions of the link.
Used a single update_reference() function with all the new segment,lane and node references.

Added functions to get the spline trajectory (with and without heading).

Completed the feature to copy the whole structure and update the references.

Added support to link road segments.

TO DO: add the functions to link road segments.