Brian Sperlongano c7e7fae9ee
Add support for Bus Rapid Transit (highway=busway) (#1271)
This PR adds support for bus rapid transit (BRT) systems, mapped with the [approved tag](https://wiki.openstreetmap.org/wiki/Proposed_features/Tag:highway%3Dbusway) `highway=busway`. BRT systems commonly appear in maps that also show light rail.  Below are two examples of BRT in such maps.

![image (1)](https://user-images.githubusercontent.com/3254090/138018375-ac1f60c3-8059-4f95-bf1d-a659ca0c0103.png)
![image](https://user-images.githubusercontent.com/3254090/138018376-f809aeb3-17ba-495e-b33c-9fe54a0fa840.png)

Since BRT is equivalent in nature to light rail systems, this PR matches the zoom level of light rail, which is rendered at zoom 11+.  BRT systems are relatively uncommon, so adding this support should have negligible impact on tile size.

Below is a data rendering of [a BRT system](https://www.openstreetmap.org/relation/4051383#map=12/40.4068/-79.8646) in Pittsburgh, Pennsylvania.

![image](https://user-images.githubusercontent.com/3254090/138021552-ce974f2f-cfbd-42a0-9848-42ed44da453e.png)
2021-11-01 08:40:07 +01:00
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2021-10-25 08:12:17 -04:00