[#77] Entities: Add AreaComContract to group area commitments together

Elwig/Windows/MemberAdminWindow.xaml.cs

@@ -807,7 +807,6 @@ namespace Elwig.Windows {
                 if (d.ShowDialog() != true)
                     return;
                 ViewModel.TransferPredecessorAreaComs = d.SuccessorSeason;
-                ViewModel.MaintainAreaComYearFrom = d.MaintainYearFrom;
                 if (IsEditing)
                     SetOriginalValue(PredecessorMgNrInput, -1);  // hack to allow user to save
                 UpdateButtons();