output csv format

[tsamaya]

Enhance readme section about CSV

use the different geoJson to csv library maybe https://www.npmjs.com/package/geojson2dsv

[tsamaya]

maybe https://github.com/mrodrig/json-2-csv

[tsamaya]

After the refactor into a TypeScript library with version 2, the next stage would be to take into account an output format to use CSV directly