mill: edit and convert wordnet data in human-readable text format

This tool validates and exports the data found in https://github.com/own-pt/own-en/ and https://github.com/own-pt/own-pt/.

See the Wiki for information about installation & configuration, file syntax & editing, how to export the data, and how it is validated.