Reevaluate cycle behavior when importing schemata
Idea:
- Connect elements in reference tree
- Prune tree model at first recursion and synbolize recursion
- Prevent endless recursion (although input ends anyway)
(from redmine: issue id 543, created on 2018-01-22tgradl, closed on 2018-12-05)
- Relations:
- relates #766 (closed)