out-of-box support for Mapbox Studio layers

[severak]

In current uMap it's impossible to use custom Mapbox Studio layer due technical differences.

Mapbox Studio layers exposes only 512x512 tiles with -1 zoomOffset.

See https://www.mapbox.com/api-documentation/#retrieve-raster-tiles-from-styles

[yohanboniface]

Thanks!
Not sure that's the best fix though. Maybe we can add those parameter in the tilelayer form instead?
With default values, that should not hurt, given that this form is advanced, so people dealing with it should not be frightened by those more options.

[severak]

My solution is IMHO more novice-friendly. Mapbox Studio has no mention about these technical differences in "Share" (and use) screen.

I copied tile URL to uMap and wondered why it's so shrinked.

[severak]

Hi - Mapbox just added possibility to return 256×256 tiles via their Styles API, see docs. This patch is thus no longer needed (for Mapbox).