in GOFEE: split get_surrogate_relaxed_candidates into candidate generation and candidate relaxation, also separated the timing of these tasks

modified moduse structure, added test of imports and changed documentation accordingly as some import statements have changed as a result

moved OperationConstraint to utils, wrote __init__ in surrogate folder and changed some class names to have capital letters, changed candidate_operations folder to candidates

removed functionallity to relax final structures in population through gofee. Should just be done afterwards

Different choices of initialization of the search should now work. Particularly structures/startgenerator and candidate_operations

rattleMutation, startGenerator, OperationsSelector, CandidateGenerator working - but test a bit more

works approximately the same as old, but with less functionality. tiny differences between old and new, when running with same seed. They do however diverge more as the searches progress.