1.0 Gazetteer spec

[tristen]

The intent of this re-write is to create a simpler general-purpose version of Gazetteer (heading in the same similar spririt as https://github.com/mapbox/gazetteer/pull/52).

1.0 version 🆕

Place bookmarks are no longer dependent on a tileset. So the following fields have been removed from the specification:

• Root level data-source value.
• highlights array containing details about the data.
• description has been renamed to place_description to match the same prefix format as place_name.

There are a few reasons for this change.

• Gazetteers should perform a smaller role as a general-purpose geographical index of locations.
• Gazetteers are useful for comparing one tileset against another.
• Accessing tileset information can be performed by the consumer using the TileQuery API.
• Supports broader use cases outside of Mapbox.
• data-source and highlights were both optional but depended on one another’s existence which introduces brittleness to the spec design.

TODOs

• [x] Add spec
• [x] Conform existing Gazetteers to new format.
• [x] Update validator + tests

[tristen]

@dasulit for review 🙇 I removed some linting that did some small validation on the GeoJSON in favor of @mapbox/geojsonhint.

[tristen]

Thanks @dasulit I think I got to a better place with the migration script, capturing values from the highlights array.