added check to avoid NP exception
added trivial condition for speedup
limited restriction to two roadsegments when placing upstream signal
points for trafficlights using recursion. Adapted distance calculation
from trafficlight to vehicle. weakened condition on lane-relevant
trafficlight (concept of lane-fine trafficlights needs re-consideration)
added continous checking of incentive/safety when performing overtaking.
This additional check is needed to avoid decision and
resulting lane-flipping in same acceleration regimes.