type: double, default:
overlap=prism, the layout is scaled by this factor, thereby
removing a fair amount of node overlap, and making node overlap removal
faster and better able to retain the graph's shape.
overlap_scalingis negative, the layout is scaled by
-1*overlap_scalingtimes the average label size.
overlap_scalingis positive, the layout is scaled by
overlap_scalingis zero, no scaling is done.