Interface refactoring

Find a design which is more intuitive and minimal.

.gitlab-ci.yml

 image: gitlab.kwant-project.org:5005/qt/research-docker
 
+before_script:
+- cd codes; export PYTHONPATH="."; cd ..
+
 run profiler:
   script:
-    - cd codes; export PYTHONPATH="."; cd ..
     - pip install memray pyinstrument
     - python profiling/graphene.py
   artifacts: