changed version number to 0.4.0

updated version number is setup.py, ready for 0.3.0 release

removed mathjax configuration in docs/conf.py

used importlib.resources to load the matplotlibrc

prepared release 0.1.7

prepared release 0.1.6

added 'jupyter-notebook' string among 'keywords'

prepared for version 0.1.4

prepared release 0.1.3

added GitHub worflow to automatically release on pypi