Copying of molecule objects loaded from custom xyz files fails

[YHordijk]

When loading a molecule using TCutility.molecule.load we capture information about the molecule and the atoms in their respective flags attribute. Because flags is a TCutility.results.result.Result object there will be issues whenever you call the copy method of the molecule. This method is very often used (for example in workflows) and we therefore should fix this. One way of fixing it is to overload the __reduce__ method of the TCutility.results.result.Result class. This method should return a single string specifying the name and namespace of the class. This then tells copy.deepcopy (which plams uses) what the class is supposed to be.

[YHordijk]

I have added a test-case. You can see that it will pass if we define the __reduce__ method, but will fail if we do not define it. There seems to be some weird stuff going on under the hood of copy.deepcopy, but I don't know enough about the deeper parts of Python to fully understand it. Documentation is also a bit complicated a scarce about this topic.