Merge branch 'refactor_packaging' into 'master'

src/pystencils/runhelper/__init__.py

src/pystencils/runhelper/db.py

src/pystencils/runhelper/parameterstudy.py

src/pystencils/session.py

src/pystencils/simp/__init__.py

src/pystencils/simp/assignment_collection.py

src/pystencils/simp/simplifications.py

src/pystencils/simp/simplificationstrategy.py

src/pystencils/simp/subexpression_insertion.py

src/pystencils/simplificationfactory.py

src/pystencils/slicing.py

src/pystencils/spatial_coordinates.py

src/pystencils/stencil.py

src/pystencils/sympyextensions.py

src/pystencils/timeloop.py

src/pystencils/transformations.py

src/pystencils/typing/__init__.py

src/pystencils/typing/cast_functions.py

src/pystencils/typing/leaf_typing.py

src/pystencils/typing/transformations.py