ref #8543 fix missing footnoteListKey default fallback
ref #8543 complete removal of annotation footnote code, also removing deprecated methods
ref #8543 testing for FOOTNOTE_KEY_SUFFIX_ANNOTATIONS in use by throwing an exception
ref #8543 deprecating, cleaning up and documentation of footnote functions
ref #8543 further unification of annotation and source handling
ref #8543 renaming and documentation towards unification of annotation and other footnotes
ref #8543 further harmonizing footnote functions
ref #8543 removing useless code and cleaner footnote functions
ref #8543 moving footnote functions to separate inc file