Implement "inverted" feature for group nodes

Reverse the order of the subgraph (and invert the subnodes itself)...

added enhancement label

changed milestone to %v0.1

assigned to @u.eisenbarth

changed time estimate to 1w

created branch 14-implement-inverted-feature-for-group-nodes to address this issue

mentioned in merge request !5 (merged)

added 1h of time spent

mentioned in commit 550d04b1

closed with merge request !5 (merged)