Added some functions:

* 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, lane, lane index, segment, segment index and pose to a given point.
* to get the number of lane objects and a reference to them.
* to udpate the index of lanes and nodes when creating new roads.
* to update the node index from a path.