merge from main

examples/diatomic_molecule.ipynb

examples/graphene_extended_hubbard.ipynb

examples/mexican_hat.ipynb

meanfi/__init__.py

meanfi/kwant_helper/__init__.py

meanfi/kwant_helper/kwant_examples.py

meanfi/kwant_helper/utils.py

meanfi/mf.py

meanfi/model.py

meanfi/observables.py

meanfi/params/__init__.py

meanfi/params/param_transforms.py

meanfi/params/rparams.py

meanfi/solvers.py

meanfi/tb/__init__.py

meanfi/tb/tb.py

meanfi/tb/transforms.py

meanfi/tb/utils.py

meanfi/tests/test_graphene.py

meanfi/tests/test_hat.py