Merge remote-tracking branch 'origin/master' into arm64

.gitlab-ci.yml

doc/conf.py

...books/05_tutorial_phasefield_spinodal_decomposition.ipynb

doc/notebooks/06_tutorial_phasefield_dentritic_growth.ipynb

pystencils/backends/arm_instruction_sets.py

pystencils/backends/simd_instruction_sets.py

pystencils/field.py

pystencils/gpucuda/indexing.py

pystencils/gpucuda/kernelcreation.py

pystencils/stencil.py

pystencils/transformations.py

pystencils_tests/test_buffer.py

pystencils_tests/test_buffer_gpu.py

setup.py