Modeler misbehaves during an undo action for a DbEntity
How to reproduce:
Precondition: In a project with at least 2 DbEntities, DbEntity1 and DbEntity2, with ObjRelationship and ObjAttribute in their lists.
1. Go to DbEntity1 and remove an existent DbAttribute
2. Switch to the DbEntity2 to visualize its attribute(s) and relation(s)
3. Go to main menu and select undo
4. Visualized DbRelationship(s) list is incorrect, modeler only refresh the DbAttribute(s) list