Merge branch 'f-transformers' into 'dev'

CHANGELOG.md

src/caoscrawler/converters.py

src/caoscrawler/default_transformers.yml

src/caoscrawler/scanner.py

src/caoscrawler/transformer_functions.py

src/doc/cfood.rst

src/doc/converters.rst

unittests/test_converters.py

...ests/test_directories/test_transformers/Day_Mon/README.md

...ests/test_directories/test_transformers/Day_Tue/README.md

...ests/test_directories/test_transformers/Day_Unk/README.md

unittests/test_directories/test_transformers/cfood.yml

unittests/test_scalars_cfood.py

unittests/test_scanner.py

unittests/test_transformers.py

unittests/test_variable_substitutions.py