MAINT: Make formatting consistent

[MartinThoma]

• black: Code formatting
• isort: Sort imports
• Remove trailing spaces and end files with newline

All of this can be done automatically before each commit by installing pre-commit:

$ pip install pre-commit $ pre-commit install

[MartinThoma]

This commit is purely about style. It should not have any effect on the code execution.

The changes were done by adding two files (.isort.cfg and .pre-commit-config.yaml) and running

pre-commit run --all-files

The black formatter is supported by the Python Software Foundation (psf). There are two reasons to use such an automatic code formatter:

1. The code will look familar to anybody who uses a similar formatter.
2. No more discussions about formatting.