format tests for atom, docx, odt, and xlsx

formats/atom_format.py

formats/docx_format.py

formats/odt_format.py

formats/xlsx_format.py

tests/data/Atom_SH_Feldblockfinder_OpenGBD.xml

tests/test_atom_format.py

tests/test_docx_format.py

tests/test_odt_format.py

tests/test_xlsx_format.py