New features: * handle visibility and form/syntax of linked references based on RWA Online configuration * show/hide source images with respect to their legal status in annotation preview area (#7) * show/hide irrelevant sources (#8) * add new RWA annotation category "RWA erratum" * support for "footnotes" and figures in critical remarks Fixes: * fix problems with virtual parts concordances and concordance navigator * fix some layout problems in navigator