wcst_import - FIX - select proper GRIB messages per band to import

[Bang Pham Huu]

Currently, wcst_import considers all grib messages having the same shortName in a GRIB file to build one-band coverage.

e.g. shortName = t then it is temperature data.

However, the weather data shows that, it is incorrect, because, the temperature in a GRIB file can be separated to different one-band coverages.

For example: output of grib_dump tool

• Temperature - Isobaric surface

    nameOfFirstFixedSurface = Isobaric surface ;
  
   level = 250;
  
   shortName = t;
  

and

• Temperature - Specific altitude above mean sea level

nameOfFirstFixedSurface = Specific altitude above mean sea level

 level = 250;

 shortName = t;