I've made create_measurement track and store contacts. That way if I call get_contacts, I really get all contacts, so I can also get the right shape of the feet. This does mean that I need to change the workflow, since now I don't want to create a new contact when I've labeled them, but update the old one
Refactoring the model class, since they rely too much on the order in which things are done
Shouldn't I be able to remove the self.measurement parts from create_measurement again?
fixes #71