Eliminated the 'Dao.Interpreter.HasIterator' class and replaced it with the 'Dao.Interpreter.ReadIterable' and 'Dao.Interpreter.UpdateIterable' classes. These new classes are a much improved interface to Dao iterators that can be used in "for" loops. I also incorporated these changes into the 'Dao.Interpreter.execute' instance of 'Dao.Interpreter.ScriptExpr' for the 'Dao.Interpreter.ForLoop' constructor, and I have written a the "tests/list.dao" program to test it. As of right now it seems to be working well.