integrate iteration slices. buffer test cases now complete.

.flake8

src/pystencils/backend/arrays.py

src/pystencils/backend/ast/collectors.py

src/pystencils/backend/ast/kernelfunction.py

src/pystencils/backend/ast/nodes.py

src/pystencils/backend/ast/transformations.py

src/pystencils/backend/ast/tree_iteration.py

src/pystencils/backend/constraints.py

src/pystencils/backend/emission.py

src/pystencils/backend/jit/cpu_extension_module.py

src/pystencils/backend/jit/legacy_cpu.py

src/pystencils/backend/jit/msvc_detection.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/platform.py