added const_type: sg -> typ option; stamps now stored in REVERSE order; now supports 'draft signatures' and incremental extension: is_draft,   add_classes (supports axclasses), add_defsort, add_types, add_tyabbrs,   add_tyabbrs_i, add_arities, add_consts, add_consts_i, add_syntax,   add_syntax_i, add_trfuns, add_trrules, add_name, make_draft; added const_of_class, class_of_const (for axclasses); changed the pure signature to support axclasses (added itself, TYPE); various major internal changes;
added const_type: sg -> typ option;
stamps now stored in REVERSE order;
now supports 'draft signatures' and incremental extension: is_draft,
  add_classes (supports axclasses), add_defsort, add_types, add_tyabbrs,
  add_tyabbrs_i, add_arities, add_consts, add_consts_i, add_syntax,
  add_syntax_i, add_trfuns, add_trrules, add_name, make_draft;
added const_of_class, class_of_const (for axclasses);
changed the pure signature to support axclasses (added itself, TYPE);
various major internal changes;

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