Utilities for the FDB Fields Database

 FDB (Fields DataBase) is a domain-specific object store developed
 at ECMWF for storing, indexing and retrieving GRIB data.
 Each GRIB message is stored as a field and indexed trough semantic metadata
 (i.e. physical variables such as temperature, pressure, ...).
 A set of fields can be retrieved specifying a request using
 a specific language developed for accessing the MARS Archive.