Rewrite GROUP undo based on uuids.

This also removes the GROUP/UNGROUP-specific undo actions.

This also fixes a bunch of undo bugs when duplicating
group members, creating pins, etc.

This also fixes some undo bugs when dividing wires etc.

This also fixes some bugs with new sch items not
being created within an entered group.

pcbnew/generators/pcb_tuning_pattern.cpp

@@ -1225,17 +1225,6 @@ void PCB_TUNING_PATTERN::Remove( GENERATOR_TOOL* aTool, BOARD* aBoard, BOARD_COM
     PNS::ROUTER* router = aTool->Router();
     PNS_KICAD_IFACE* iface = aTool->GetInterface();
 
-    // Ungroup first so that undo works
-    if( !GetItems().empty() )
-    {
-        PCB_GENERATOR*  group = this;
-
-        for( EDA_ITEM* member : group->GetItems() )
-            aCommit->Stage( member, CHT_UNGROUP );
-
-        group->GetItems().clear();
-    }
-
     aCommit->Remove( this );
 
     aTool->ClearRouterChanges();
@@ -1637,7 +1626,6 @@ void PCB_TUNING_PATTERN::EditPush( GENERATOR_TOOL* aTool, BOARD* aBoard, BOARD_C
                     && bounds.PointInside( track->GetEnd(), epsilon ) )
                 {
                     AddItem( item );
-                    aCommit->Stage( item, CHT_GROUP );
                 }
             }
         }