(I decided that the larger context of the intersection is important and
shouldn't be hidden from the user)
Also
- show detail slider only if the intersection is complex
- hide the restriction editor completely if there is no real intersection
(e.g. junction of `highway=path`)
This is the part of the algorithm where trivial sections get trimmed
from the vgraph. Removing a vertex from `vertexIds` means "stop checking
this one". But there were some situations where it could get removed
twice, so we now just verify that `vertexId` is actually in the array
before calling `splice`.
Bryan Housel