Updated logic to create hierarchy in this form:

  EH/4/
      centre.json
          [55.96485,-3.2639]
      2.json
          {"AA":["55.9583","-3.2495"],"AB":["55.9589","-3.2508"],"AD":["55.9597","-3.2512"], ...}

  Results in ca. 13704 files/ 3003 directories.
  File size from 13 bytes to 10k
  Overall size: ca. 200MB
  Time taken to generate files: ca. 1 minute