Enable creation of MaskedCircuit from logging results or pickled object

[eileen-kuehn]

Currently during logging of results a stream of json objects is saved. We should either consider adding as many information to restore the MaskedCircuit after training or directly provide a pickled object. I currently tend to supporting the pickling as this might also streamline readability of the json stream. I suppose we will not use information from the parameter array or mask to create our plots. If we do, we should maybe keep those in the json stream.