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.