MapNode describes a node in a Road Map.
It has a position as well as an optional name, in addition to some parameters.
Inherits from pilot.MapElement.
parent = -1
Parent node id, if any.
If a pilot.MapNode or pilot.MapStation has a parent its position (and orientation) is defined relative to it.
Optional node name, usually a station name.
2D (x, y) map position, see math.Vector2d.
3D (x, y, yaw) pose offset relative to parent, see math.Vector3d.
If parent is a pilot.MapStation the offset is relative to its orientation.
A set of drive flags for this node, see pilot.drive_flags_e.