~lyndsysimon/columnist

Add JSONFormatter
Update README
Refactor formatters as a module
Add Flake8, GitLab CI
Add CSVFormatter
Allow explicit column ordering
Add tests for ColumnDescriptor
Refactor away Report._name_from_class
Add some type annotations
Add roadmap to README
Refactor into better-named files
Fix README formatting
Add docstrings to tests
Initial commit