Hi,

thank you for looking over my changes. 

The difference between `turn:lanes` and `placement` lies in their use-case: While `turn:lanes` is mainly useful for routing, `placement` has additional properties for advanced rendering engines, such as: https://a-b-street.github.io/osm2streets/#18.49394506349628/42.19918/24.64866

The `placement` tag allows you to draw the highway in a straight line instead of drawing light curves, to touch the middle of the road as often as possible. This is especially useful for entry and exit lanes, that disappear after a short amount of distance. Therefore the mapping is more accurate than just using the `turn:lanes` tag.

See the wiki for more details: https://wiki.openstreetmap.org/wiki/Proposal:Placement

P.S.

a 2D view showcases the use of placement even more: 

with placement: http://osm.mueschelsoft.de/lanes/?wayid=1158813897&start=1&country=de&placement&adjacent&lanewidth&usenodes&extendway

without placement: http://osm.mueschelsoft.de/lanes/?wayid=1158823100&start=1&country=de&placement&adjacent&lanewidth&usenodes&extendway

I am aware, that it is possible to infer some rendering info from turn:lanes,  by using heuristics, but this can never be accurate, because the ways before and after the exit should also have `turn:lanes` info or some default can be assumed. This will break on complex junctions. Alternatively the `connectivity` could be used. This seems overcomplex for this usecase to me.

Have a great evening!