Merge branch 'f-xml-converter' into 'dev'

CHANGELOG.md

README_SETUP.md

README_SETUP.md

src/caoscrawler/__init__.py

src/caoscrawler/cfood-schema.yml

src/caoscrawler/converters.py

src/caoscrawler/default_converters.yml

src/caoscrawler/structure_elements.py

src/caoscrawler/xml_converter.py

src/doc/README_SETUP.md

src/doc/cfood.rst

src/doc/concepts.rst

src/doc/converters/cfood_definition.rst

src/doc/converters/custom_converters.rst

src/doc/converters/further_converters.rst

src/doc/converters/index.rst

src/doc/converters/standard_converters.rst

src/doc/converters/transform_functions.rst

src/doc/index.rst

unittests/test_converters.py