DADict use self __setitem__ instead of elements __setitem__

[jpagh]

Since the default __setitem__() method in a DADict looks like this:

    def __setitem__(self, key, the_value):
        self.elements[key] = the_value

I wanted to update all of the methods in a DADict to use the class's self.__setitem__() via self[key] = notation instead of the elements's self.elements.__setitem__() via self.elements[key] = notation. This would allow me to be able to override only the __setitem__() method in my custom DADict class (which validates the key before assignment) rather than having to validate the key in a few different places which required additional method overrides.

The method new() already does this (self[parg] = None), but the method initializeObject() does not (self.elements[entry] = newobject).