CRS support in GeoJSON

[andrea-perego]

At the time of the release of GeoDCAT-AP v1.0 (December 2015), GeoJSON provided support to arbitrary coordinate reference systems (see the original specification).

In the new specification (RFC 7946), standardised in the framework of IETF, this is no longer the case, and the only supported coordinate reference system is CRS84 (i.e., WGS84 lon/lat) - see RFC 7946, Section 4.

Because of this, the use of GeoJSON in GeoDCAT-AP might need to be reconsidered - at least by including a caveat, and some guidance on when and how to use it.