Merge branch 'SmallCleanUp' into 'master'

.gitignore

README.md

doc/sphinx/api.rst

doc/sphinx/enums.rst

doc/sphinx/kernel_compile_and_call.rst

pystencils/backends/cbackend.py

pystencils/data_types.py

pystencils/enums.py

pystencils/fast_approximation.py

pystencils/field.py

pystencils/kernelcreation.py

pystencils_tests/test_field.py

pystencils_tests/test_fvm.py

pystencils_tests/test_vectorization.py

pytest.ini