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.

The get_closest*() functions have a new parameter to limit the search to the links belonging to a lane.
The parent information no longer includes the length of the link.

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 node and update its references.
Added a function to clean any invalid reference.

  * A function to get the link ending at a given node.
  * A function to get the closest link to a point.
  * A function to get the set to closest points to a given point.

Got the curvature information to generate the spline for each link.

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

Added a referecne to the parent road segment in the COpendriveRoadNode class.
In the destructor, only the link starting at the current node are deleted to avoid double free.

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.