Implement __geo_interface__ #147
Description
Instead of the homegrown GeoJSON implementation, we should consider implementing __geo_interface__ to enable interoperability with widely used geospatial Python modules such as shapely, geojson and fiona.
I haven't looked into this much yet, but I am considering it for the osmdiff project that I am currently refactoring.
/cc @sgillies who came up with __geo_interface__ in the first place.