rename the XX_slot classes to SlottedXX

move to slotted and slots (wip)

test/sol/class_send/test_class_send_inherited.rb

@@ -31,7 +31,7 @@ module Sol
     def test_receiver
       assert_equal SlotMachine::ArgumentTransfer,  @ins.next(1).class
       assert_equal 0,  @ins.next(1).arguments.length
-      assert_equal ObjectSlot,  @ins.next(1).receiver.class
+      assert_equal SlottedObject,  @ins.next(1).receiver.class
       assert_equal Parfait::Class,  @ins.next(1).receiver.known_object.class
       assert_equal :Space,  @ins.next(1).receiver.known_object.name
     end