Merge

What to do when merging a feature branch back to the master

• Update the release notes
• ensure that all new classes/functions are mirrored in the Python interface
  • unless tested by a demo or acceptance test, add a Python unit test to check the interface
• ensure that all modifications to acceptance tests and/or demos are also mirrored in the corresponding Python tests/demos
• Start from a clean repository (to notice files that were not committed) and run the script tools/test_all.sh
  • checks for g++, clang++ that everything builds and all tests run without errors
• merge; fix conflicts
• check tests again (unit tests, demos) unless the master was just fast-forwarded
• remove feature branch locally and on server