Block markup: maintain output version within tree values (in accordance with String) -- changes operational behaviour wrt. print_mode; to_ML/from_ML: proper handling of markup;
Block markup: maintain output version within tree values (in accordance with String) -- changes operational behaviour wrt. print_mode;
to_ML/from_ML: proper handling of markup;

MerelyAPseudonym/isabelle,MerelyAPseudonym/isabelle,MerelyAPseudonym/isabelle,MerelyAPseudonym/isabelle,MerelyAPseudonym/isabelle,MerelyAPseudonym/isabelle