Create convert_yaml file, with basic command-line options script.
Restructure test data.
Reorganise test file, for use with YAML tests.
Reorganise test data for use with YAML tests.
Implement 'convert hyphens'.
Improve 'convert hyphens' test data.
Implement 'convert date'.
Improve hyphens test.
Implement 'convert tags'.
Implement 'convert metadata'.
Implement 'convert full'.
Tidy up 'convert date'.
Implement 'convert summary'.
Tidy up variable naming.
Implement 'convert everything'.
Rename 'convert' to 'convert_everything'.
Implement file saving.
Delete stub 'test_convert' test.
Refactor everything into a single module.
Delete obsolete modules.