Summary
- more robust syntax;
- unused;
- clarified document export names;
- tuned signature;
- tuned;
- tuned;
- avoid former verbose_latex, which has been renamed to verbose in 52030acb19ac;
- compose Latex text as XML, output exported YXML in Isabelle/Scala;
- more direct index_entry: no positions required -- text is eventually moved to .ind file;
- clarified signature;