Updated logic to create hierarchy in this form:

  EH/4/
      centre.json
          [55.96485,-3.2639]
      2J.json
          {"A":["55.9609","-3.2295"],"B":["55.9595","-3.2321"],"D":["55.9587","-3.2345"], ... }

  Results in ca. 150K files/directories.
  File size from 13 to 521 bytes
  Overall size: 1.7G
  Time taken to generate files: ca. 2 minutes