Calling destructors works fine

[Stefan_Salewski]

The gintro README contains still a warning from early ARC days that users may 
have to declare their own destructors if the intent to subclass widgets:

<https://github.com/StefanSalewski/gintro#extending-or-sub-classing-widgets>

But from a recent test I get the feeling that this is not really necessary any 
more. With modules tt.nim and t.nim I get:
    
    
    # module tt.nim
    type
      O1* = ref object of Rootref
        i*: int
    
    when defined(gcDestructors):
      proc `=destroy`(o1: var typeof(O1()[])) =
        echo "destroy O1 ", typeof(o1)
    
    
    Run
    
    
    module t.nim
    import tt
    
    type
      O2 = ref object of tt.O1
        j: int
    
    type
      O3 = ref object
        o1: tt.O1
    
    type
      O4 = object
        o1: tt.O1
    
    proc main =
      var o1: tt.O1
      new o1
      echo o1.i
      
      var o2: O2
      new o2
      echo o2.j
      
      var o3: O3
      new o3
      new o3.o1
      
      var o4: O4
      new o4.o1
    
    main()
    
    
    Run
    
    
    salewski@nuc /tmp/hhh $ ./t
    0
    0
    destroy O1 O1:ObjectType
    destroy O1 O1:ObjectType
    destroy O1 O1:ObjectType
    destroy O1 O1:ObjectType
    
    
    Run

So the destructor is always called for the parent base class, no need for users 
to declare own destructors any more. Is this new for latest Nim 1.4?