Self intersecting lane markings

[TrackerSB]

Is your feature request related to a problem? Please describe.
When roads are self intersecting their road markings are potentially as well. Currently SimNodes throw some internal Python error and generated the whole environment leaving out the affected road markings.

Describe the solution you'd like
Either find a method which does not include the generation of offset lines or detect potential points where road markings are self intersecting beforehand and generate multiple separate road markings which smoothly follow each other.

Describe alternatives you've considered
This feature could also be solved by the introduction of crossings in the road markings.