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Project infrastructure changes:
- Default GitHub branch is now "main".
Deprecations and future warnings:
- The Tile constructor in mercantile 2.0 will refuse to make tiles with X and Y
indexes outside of the range 0 <= value <= 2 ** zoom. It will also require
indexes to be integers.
New features:
- Add ``geojson_bounds`` to get the bounding box of a GeoJSON geometry,
feature, or collection (119).
- Add ``minmax`` to get minimum and maximum x and y tile coordinates.
- Add ``neighbors`` function and command to get adjacent tiles (118).