maxspeed:type/source:maxspeed support

[starsep]

Currently maxspeed is not calculated from maxspeed:type/source:maxspeed in car_maxspeed (Transportation -> Individual Traffic -> Maxspeed).
It could be implemented via https://github.com/westnordost/osm-legal-default-speeds library.

Examples:
https://osm.org/way/306610860
https://www.openstreetbrowser.org/#map=18/52.23888/21.00985&categories=car_maxspeed

https://osm.org/way/4936860
https://www.openstreetbrowser.org/#map=19/52.22869/21.00153&categories=car_maxspeed

[plepe]

Interesting, I will look into it!