config/sched: subtask target can know be inherited from supertask
models: no longer call beginResetModel()/endResetModel()

Rather remove every row and then insert every new row when resetting the
whole model.
Rationale: QItemSelectionModel do not send selectionChanged() signal
when the model is reset, therefore views (or any other connected object)
are not notified that selection has changed, whereas they are when
removing rows containing selected items.
paramset: fixed evaluation of % when used as an escape character