• if objects in the "expected" structured have an as_test_deep_cmp
  method, it will be called and its return (which should be a
  Test::Deep::Cmp object) will be used as the test for that location in
  the structure
  
• internal undocumented class_base routine has been replaced
  with a different, clearly private routine
  
• the LeafWrapper is also used for objects with an unknown reftype
  (like LVALUE or other weird ones)