Add rankSlope so we need less RAM access in Dijkstra
Add rankSlope so we need less RAM access in Dijkstra

this reduces n*n paths for 17 Landeshauptstädte from
950 ms to 750 ms and brings the Dijkstra part of
ShortestPathCH below 10 ms

ToureNPlaner/tourenplaner-server,ToureNPlaner/tourenplaner-server,ToureNPlaner/tourenplaner-server,ToureNPlaner/tourenplaner-server