renamed show_var_qmarks to show_question_marks; string_of_vname: improved treatment of \<^isub> and \<^isup>;
renamed show_var_qmarks to show_question_marks;
string_of_vname: improved treatment of \<^isub> and \<^isup>;

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