Changes revolving route path

 * Simplify route in preview if  it has more than 100 points
 * Creating new instance of path in preview
 * builing path dynamically based on bounding box in routing mode
 * handing reroute drawing with the same on demaind path drawing
it's iffy not to have this logic tested at all ... I will give it another go and add the first and last point offscreen while I am at it ;)