[ENH] Using some Python coding best practices for open source repositories

[fabianegli]

I propose that tis project adopts some of the standard Python development tools to make contributions easier and reduce some of the burden of new contributors.

• black and black-disable-checker for code formatting
• isort to systematically sorting the imports
• pylint to spot and fix mistakes, errors and code smells

Further tools that are not yet very useful here but might become handy in the future

• blacken-docs for documentation
• mypy if type annotations become a thing in this package.