Fixed a couple funky entity relatinoships

prs.classes/Entities/Employee/EmployeeProduct.cs

@@ -27,7 +27,7 @@ namespace Comal.Classes
         public DateTime Issued { get; set; }
 
         [NullEditor]
-        [EntityRelationship(DeleteAction.SetNull)]
+        [EntityRelationship(DeleteAction.Cascade)]
         public StockMovementLink IssuedMovement { get; set; }
 
         [TimestampEditor(Visible = Visible.Default)]
@@ -35,7 +35,7 @@ namespace Comal.Classes
         public DateTime Returned { get; set; }
 
         [NullEditor]
-        [EntityRelationship(DeleteAction.Cascade)]
+        [EntityRelationship(DeleteAction.SetNull)]
         public StockMovementLink ReturnedMovement { get; set; }
 
         [TimestampEditor(Visible = Visible.Default)]

prs.classes/Gantt/GanttRelationship.cs

@@ -9,10 +9,10 @@ namespace Comal.Classes
         [EntityRelationship(DeleteAction.Cascade)]
         public TEntityLink Parent { get; set; }
 
-        [EntityRelationship(DeleteAction.Cascade)]
+        [EntityRelationship(DeleteAction.SetNull)]
         public TStageLink Predecessor { get; set; }
 
-        [EntityRelationship(DeleteAction.Cascade)]
+        [EntityRelationship(DeleteAction.SetNull)]
         public TStageLink Successor { get; set; }
 
         public GanttRelationshipType Type { get; set; }