add basic balloon plot functionality

Created by: hoelzer

For the manuscript, I generated a balloon plot and in that context, I also added the basic functionality and code to the pipeline:

It needs polishing but provides the basic functionalities so I would like to merge it into master.

Can you please check @mberacochea ?

Review: Approved

Looks good :).

I need to merge this into my cwl-docker branch later.

approved this merge request