Minimize dependency

[jbrezmorf]

Python implementation still depends on the Python. Moreover if we want to separate it to more modules it must probably be installed. That could make problems if pip and/or venv is not available. To this end we propose:

1. use only standard Python packages
2. Do not use setuptools, make main bash scripts that calls python with modified PYTHONPATH.
3. For stable pieces of the code reimplement it in pure bash/sh.