Tweet: test pickle, unpickle, fix recursion

[achimgaedke]

Ok, I have been bitten by this before, so I knew there was something in the python docs... somewhere...

https://docs.python.org/3/reference/datamodel.html?highlight=__getattr__#object.__getattribute__

In order to avoid infinite recursion in this method, its implementation should always call the base class method with the same name to access any attributes it needs, for example, object.getattribute(self, name).

Here is a test and an implementation of the suggestion above... as the mixin class elevates data as the origin of all state and maps itself again into it...