Create a "routing" label placement mode

Nobody has claimed this yet.

migrated from https://github.com/mapbox/DEPRECATED-mapbox-gl/issues/1

... or perhaps create a custom label placement plugin API

> @ansis:
> Dynamically adapting what labels are shown and how they look based on a route.
>
> For example:
> - making roads used by the route have bigger labels
> - deemphasizing roads that don't cross the route
> - placing labels for intersecting roads close to the intersection
> - adding pois near turns to make them easier to identify
>
> I don't think this would be entirely implemented within core mapbox gl but we would need to implement some apis to make this possible.

Start with the migrated issue discussion and review the project's existing label-placement extension points. Done means defining and implementing a routing mode or plugin API that supports route-aware label visibility, emphasis, placement, and nearby POIs, with the scope of the core changes made explicit.

Written by the indexing model from the issue text.