[Tagging] Feature Proposal - RFC - footway=link

[Allroads]

All waylines inside a area:highway=footway footway=sidewalk is a 
highway=footway footway=sidewalk
When there is a connection to the road, inside the area:highway=footway, 
footwalk=sidewalk is till the barrier=kerb.

Only on the road from barrier=kerb till the centerline of the road (wayline) 
could be highway=footway footway=link.
When the footway crossed the total road, then footway=crossing is used.

This is a example, where the highway=footway footway=sidewalk, is drawn till 
the barrier=kerb from a cycleway, then a unmarked crossing.
https://josm.openstreetmap.de/raw-attachment/ticket/18213/noselectwayline.png