Enhancement pattern: ignoring empty values

csv2rdf4lod-automation is licensed under the [Apache License, Version 2.0](https://github.com/timrdf/csv2rdf4lod-automation/wiki/License)

      conversion:interpret [
         conversion:symbol "", "-", "- ";
         conversion:interpretation conversion:null;
      ];

Can be added to the entire conversion:ConversionProcess or to a specific conversion:ColumnEnhancement.

For more detail, see conversion:interpret.