Improved shared route line Ddrawing for clearer topos

For routes starting from the same point, the shared section should be drawable in such a way that a subsequently drawn route can be anchored to a desired point on a previously drawn route. In the topo image, the common section of the route lines would be displayed as a single line, with the numbers of both routes visible at its starting point. After the junction, the route numbers would be displayed on their respective individual lines. If a route with a shared line is modified, the user should be asked if they want to change the shared section for all routes. This change aims for a clearer topo view and avoids cluttering the image with overlapping lines.