Functional extension of mappings and the execution

Collective task; mainly there are some problems and limitations that need to be solved:

  • Multiple input elements should be allowed
  • Each input requires treatment by grammars/functions
  • Object level needs to be configurable: produce leaves only or duplicate parents
  • Major UI adaptions need to reflect new metamodel/functionality

(from redmine: issue id 536, created on 2018-01-22tgradl, closed on 2018-01-22)