renamed 'defns' to 'defs'; removed 'sigclass'; replaced parents by enclose; exported parens, brackets, mk_list, mk_big_list, mk_pair, mk_triple; various minor internal changes;
renamed 'defns' to 'defs';
removed 'sigclass';
replaced parents by enclose;
exported parens, brackets, mk_list, mk_big_list, mk_pair, mk_triple;
various minor internal changes;

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