Fix the assumed spherical earth radius for GRIB1 data. #241
Description
Possibly, this has always been wrong.
The gribapi has recently changed on that assumption : see this comment.
As it's a breaking change, and come quite late, we included a fix to preserve the 'old' behaviour for release v0.16,.
It might in fact be "more correct" to use the gribapi-provided default 'radiusOfTheEarth' parameter,
so this needs re-considering.