Add ability to output in {geodk} friendly format

[aleksanderbl29]

It would be handy to be able to easily (maybe via pipe-syntax) match statistics to their the appropriate geographics

[aleksanderbl29]

I have begun working on this. In feat/geodk-friendly I have pushed a minimal implementation of the needed S3-things for this side of the integration. Work now commences in the {geodk}-repo

[aleksanderbl29]

This issue should not have been closed. Will keep it open as long as the integration is work in progress.

The s3 constructors for all geographical levels (provided by the API, that is) have been implemented and it would be trivial to add more. Now work actually begins in {geodk} dkstat-integration