Merge branch 'refactor_packaging' into 'master'

src/pystencils/include/PyStencilsField.h

src/pystencils/include/__init__.py

src/pystencils/include/aesni_rand.h

src/pystencils/include/arm_neon_helpers.h

src/pystencils/include/gpu_defines.h

src/pystencils/include/half_precision.h

src/pystencils/include/myintrin.h

src/pystencils/include/philox_rand.h

src/pystencils/include/ppc_altivec_helpers.h

src/pystencils/integer_functions.py

src/pystencils/integer_set_analysis.py

src/pystencils/jupyter.py

src/pystencils/kernel_contrains_check.py

src/pystencils/kernel_decorator.py

src/pystencils/kernel_wrapper.py

src/pystencils/kernelcreation.py

src/pystencils/node_collection.py

src/pystencils/placeholder_function.py

src/pystencils/plot.py

src/pystencils/rng.py