introduce code style checking with black and linting with flake8
- 5fb61e8d gitweb: fix issues reported by flake8
- 79778e59 flyspray: reformat python code with black
- e99546a6 gitweb: reformat python code with black
- d061cd48 ci: add Python code style checking and linting
- 11c21125 gitweb: add reformat-lint target
- 278c5626 add .flake8 config file
TODO: flake8 issues reported in flyspray
code.