MAINT: Documentation, formatting, typos, error messages, linkahead

src/caoscrawler/converters.py

src/caoscrawler/crawl.py

src/caoscrawler/hdf5_converter.py

src/caoscrawler/identifiable.py

src/caoscrawler/identifiable_adapters.py

src/caoscrawler/scanner.py

src/caoscrawler/utils.py

unittests/test_crawler.py