Regular Maintenance

Update year in copyright headings

Every file shoud contain a copyright header with a year range. The current year can be updated every year with a command line like

sed -i 's/-202X/-202Y/g' *.py ./tests/**/*.py ./inyoka/**/*.py LICENSE ./**/*.html ./**/*.less ./**/*.js

(replace X with the last number of the previouse year and Y with the current year.)

git grep can help to find missed occurences.