Should fix #3306: when parsing XML, if "settings" tag is found within "gui", then it's a preferences XML - so it's not an old specific file for which we need some backward compatibility

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@26229 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e