The spline class returns maximum length when the is no closest point belonging to the spline.
All other classes check the returned length to check for the existance of the closest point.

* to get the pose at a given distance in the link.
* to get the curvature at a given distance in the link.
* to get the closest node, node index and pose to a given point.
Added the link reference update to the clone(),get_sub_lane(), update_start_node() and update_end_node() functions.

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 a function to add additional node in unconnected lanes.
Solved some bugs.

Added functions to create a copy of the lane and update its references.
Added a function to clean any invalid reference.
Added a function to get the closest point on the lane to a given point.

  * New nodes are first linked before adding them to the lane. This avoids using invalid lane end positions.
  * In the get_start_point() and get_end_point() functions: the lane object address is compared instead of the lane ID.
  * In the get_start_point() and get_end_point() functions: for left lanes, the last node is used instead of the first one to get the desired point.

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

Added a function to return the length of a lane.
Solved a bug with the names of the road marks.
Solved a bug when kinking two nodes in the same lane.

Road nodes from diferent roads at the same location are fused.
Road nodes can belong to multiple lanes: each has a vector of parent lanes and geometries.

Added support to link road segments.

TO DO: add the functions to link road segments.