add_notation: permissive about undeclared consts; add_abbrevs: allow qualified names; tuned;
add_notation: permissive about undeclared consts;
add_abbrevs: allow qualified names;
tuned;

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