First autogenerated walberla app that compiles without errors

src/pystencils_autodiff/framework_integration/astnodes.py

src/pystencils_autodiff/framework_integration/printer.py

src/pystencils_autodiff/walberla.py

src/pystencils_autodiff/walberla_user_defintions.tmpl.hpp

src/pystencils_autodiff/wald_und_wiesen_simulation.py

tests/test_walberla.py