Add rendering of "ref" for track roads

[jeisenbe]

Related to #2052

Changes proposed in this pull request:

• Add rendering of "ref" codes and numbers for track roads, using a similar style as used for residential and unclassified roads

Explanation

Track roads, tagged with highway=track, are used to access agricultural and forestry areas. Many of these small roads are unnamed, but in some areas it is common to use a reference number or string of letter and numbers to refer to such roads. For example, Forest Service roads in North America often have a ref, without a name, or sometimes both.

Adding rendering of the ref will help with routing in these areas. The style of rendering is rather subtle, using the same style as the name text label rendering.

One issue is that the ref layer is rendered first, so if there is not space for both the name and the ref, the ref alone will be rendered. But in practice, most track roads with refs are long, so this problem is much more common on highway=residential, which already has a ref rendering. If the ref is more commonly used than the name, this could be seen as a benefit.

Test rendering with links to the example places:

Allotments in the city of Hamburg, Germany
https://www.openstreetmap.org/#map=15/53.6185/9.9781
z15 Before

z17 Before

z15 After

z17 After

Well-mapped rural area in Maine, USA
https://www.openstreetmap.org/#map=15/45.7108/-68.8079
z15 Before

z17 Before

z15 After

z17 After

https://www.openstreetmap.org/#map=17/45.69977/-68.79609

Old State Road, Maine
https://www.openstreetmap.org/#map=18/45.80773/-68.90040
z18 Before

After

Logan Pond Trail, Maine
https://www.openstreetmap.org/#map=16/45.8244/-68.8615
z16 Current

After

[Penegal]

Is this in production? If so, it seems to not work everywhere, for instance here: https://www.openstreetmap.org/#map=17/48.34782/6.13247

[kocio-pl]

No, the deployment has not yet happened for some reason: openstreetmap/chef#218

[Penegal]

Ok, thanks and sorry for the noise.