Transform scripts into clean Python modules #64

This repository is working well, but is a mess to work with.
Changing the scripts to a Python module would have some advantages:

• Register module in Python Package Index
• Versioning of dependencies via pip instead of installing requirements.txt manually
• Version OpenModelicaLibraryTesting
• Testing parts of the module
• Chance to
  • Improve documentation
  • clean up the code base

For e.g. https://github.com/OpenModelica/openmodelica-library-testing-action it would also simplify things. No need to clone the repository on some specific hash but simply install and cache with pip.