Refactor packaging, part I

Relates to #75 (closed).

Move all project info to pyproject.toml.

Tasks:

• Static Project Info
• Register and run versioneer
• Register Cython extension modules
• Clean up package data files & manifest
• Remove quicktest action from setup.py and realize quicktests some other way -> introduced quicktest.py

Notes:

• The quicktest command in setup.py uses the distutils command interface, but distutils is deprecated since Python 3.10. We must find some other way to realize quicktests.

pystencils/boundaries/createindexlistcython.pyx

-# distutils: language=c
-# Workaround for cython bug
-# see https://stackoverflow.com/questions/8024805/cython-compiled-c-extension-importerror-dynamic-module-does-not-define-init-fu
-WORKAROUND = "Something"
+# cython: language_level=3str
 
 import cython