Merge branch 'fhennig/ast-vectorization' into 'v2.0-dev'

docs/source/backend/ast.rst

docs/source/backend/errors.rst

docs/source/backend/index.rst

src/pystencils/__init__.py

src/pystencils/backend/ast/analysis.py

src/pystencils/backend/ast/astnode.py

src/pystencils/backend/ast/expressions.py

src/pystencils/backend/ast/structural.py

src/pystencils/backend/ast/vector.py

src/pystencils/backend/constants.py

src/pystencils/backend/emission/__init__.py

src/pystencils/backend/emission/base_printer.py

src/pystencils/backend/emission/c_printer.py

src/pystencils/backend/emission/ir_printer.py

src/pystencils/backend/exceptions.py

src/pystencils/backend/functions.py

src/pystencils/backend/jit/cpu_extension_module.py

src/pystencils/backend/jit/gpu_cupy.py

src/pystencils/backend/jit/jit.py

src/pystencils/backend/kernelcreation/context.py