Started refactor

src/pystencils/backend/kernelcreation/config.py

src/pystencils/backend/kernelcreation/context.py

src/pystencils/backend/kernelcreation/defaults.py

src/pystencils/backend/kernelcreation/freeze.py

src/pystencils/backend/kernelcreation/iteration_space.py

src/pystencils/backend/kernelcreation/transformations.py

src/pystencils/backend/kernelcreation/typification.py

src/pystencils/backend/platforms/__init__.py

src/pystencils/backend/platforms/basic_cpu.py

src/pystencils/backend/platforms/platform.py

src/pystencils/backend/typed_expressions.py

src/pystencils/backend/types/__init__.py

src/pystencils/backend/types/basic_types.py

src/pystencils/backend/types/exception.py

src/pystencils/backend/types/parsing.py

src/pystencils/backend/types/quick.py

src/pystencils/boundaries/boundaryconditions.py

src/pystencils/boundaries/boundaryhandling.py

src/pystencils/display_utils.py

src/pystencils/fast_approximation.py