Package to simplify the download of ECMWF open data. It implements a
request-based interface to the dataset using ECMWF's MARS language to
select meteorological fields, similar to the existing
ecmwf-api-client Python package. For details, see
* https://confluence.ecmwf.int/display/DAC/ECMWF+open+data%3A+real-time+forecasts+from+IFS+and+AIFS
* https://www.ecmwf.int/en/forecasts/datasets/open-data