Make the "group" variable accept multiple dimensions in the gantt chart

[giorgiouboldi]

In which part of the interface would this feature applies?

[ ] 1. Load your data
[ ] 2. Choose a chart
[x] 3. Mapping
[ ] 4. Customize
[ ] 5. Export

Is your feature request related to a problem? Please describe.
Make the "group" variable accept multiple dimensions.

Describe the solution you'd like
I would transform the group variable in something similar to hierarchy. With the data sample we have (Italian PMs and Presidents) I would like to group them by role and by politician for instance. If a politican has multiple role I would simply repeat it (as it happens in hierarchical charts)