rotomap-edit: pretty-print .json contents
rotomap-edit: pretty-print .json contents

Make the .json data files easier to work with by splitting their
contents over multiple lines and using sorting and indentation.

End the file with a new line to be friendlier to viewing and editing
programs.

Test Plan:
.. Add and remove a mole using rotomap-edit to cause a save ..
.. Verify that the resulting .json file is easier to work with ..

aevri/mel,aevri/mel