More sophisticated linking with one-way roads

[ansoncfit]

As of 2e3517b, ways can only be linked to if they are they are traversable in both directions. Relevant in-line commentary (some of which has since been removed):

            // If either direction of the current edge doesn't allow the specified mode of travel, skip it.
            // It is arguably better to skip it only if BOTH directions forbid the specified mode (see commented block
            // below). This system has odd effects in areas with lots of one-way streets or divided roads.
            // TODO Really, we want to allow linking to two different edge-pairs in such cases but that is more complex.
            // Do not consider linking to edges that are not marked "linkable". This excludes e.g. tunnels and motorways.
            if (!edge.allowsStreetMode(streetMode) || !edge.getFlag(EdgeStore.EdgeFlag.LINKABLE)) {
                return true;
            }
            edge.advance();
            if (!edge.allowsStreetMode(streetMode) || !edge.getFlag(EdgeStore.EdgeFlag.LINKABLE)) {
                return true;
            }
            edge.retreat();

            /*
            if (!edge.allowsStreetMode(streetMode)) {
                // The edge does not allow forward traversal with the specified mode, try the backward edge.
                edge.advance();
                // If backward traversal is also not allowed, skip this edge and try the next one.
                if (!edge.allowsStreetMode(streetMode)) return true;
            }
            */

As suggested in the comment, the current implementation leads to "odd effects" in places like Nahant:

Points along the peninsula will be linked (directly) to the ways at either end of the peninsula, because all (car) ways along the peninsula are one-way.

[abyrd]

Ah maybe I shouldn't have removed the commented out code. I was under the impression the code above it had replaced/improved upon the comment out code. In the future I'll confer before removing anything containing comments.

[ansoncfit]

Another example: origins to the east of Freeport Blvd (https://www.openstreetmap.org/way/899918275#map=16/38.5093/-121.5029) are linked to the side streets west of the one-way pair, which is not what users would expect.