Bus route plot to clearly show the overlapped routes

[RaenonX]

As of a338fc7, it's not clear to see whether a bus route is overlapped or not. Find a way to clearly indicate that.

Possible solutions

Not limited to these, but could be the starting point.

Parallel lines

For this, we may need to modify how shape data was being loaded, and apply a small offset to it.

Line with mixed colors

For this, we may need to find some scripts or builtin class to create a similar effect like this.

An alternate way of this is to have the line acts like it's combined with multiple color blocks.

[RaenonX]

I personally prefer the parallelized one. It requires not much effort (ideally), but also kinda "clean" of the overlapness. The downside of it is that if you have too many lines running in parallel, it might be pretty "fat." This may lead to some graphical distortion when you zoom out (I assume that the line width will be the same for all zooming scales).