removing those ugly slot index constants

The constants were bad enough,
but they were also at the wrong level

Now register level is defining mappings from
symbol names to indexes, by using the layout

lib/virtual/slots/message_slot.rb

@@ -1,18 +1,5 @@
 module Virtual
 
-  #TODO : this constant approach is a bit old, from before PArfait adapter
-  #      nowadays these are unneccessary as we can resolve the names by using the
-  #      layout of the class. (get Class from space)
-  TYPE_INDEX = 0
-  LAYOUT_INDEX = 1
-  CALLER_INDEX = 2
-  RETURN_INDEX = 3
-  EXCEPTION_INDEX = 4
-  SELF_INDEX = 5
-  NAME_INDEX = 6
-  FRAME_INDEX = 7
-  ARGUMENT_START = 8
-
   # The current Message is one of four objects the virtual machine knows
   #
   # Slots represent instance variables of objects, so MessageSlots
@@ -20,31 +7,31 @@ module Virtual
   # The Message has a layout as per the constant above
 
   class MessageSlot < Slot
-    def initialize index , type = Unknown , value = nil
-      super(index ,type , value )
+    def initialize type = Unknown , value = nil
+      super(type , value )
     end
   end
 
   # named classes exist for slots that often accessed
 
-  # Return is the MessageSlot(RETURN_INDEX)
+  # Return is the return of MessageSlot
   class Return < MessageSlot
     def initialize type = Unknown, value = nil
-      super( RETURN_INDEX , type , value  )
+      super( type , value  )
     end
   end
 
-  # Self is the MessageSlot(SELF_INDEX)
+  # Self is the self in MessageSlot
   class Self < MessageSlot
     def initialize type = Unknown, value = nil
-      super( SELF_INDEX , type , value  )
+      super( type , value  )
     end
   end
 
   # MessageName of the current message
   class MessageName < MessageSlot
     def initialize type = Unknown, value = nil
-      super( NAME_INDEX , type , value  )
+      super( type , value  )
     end
   end
 end