improved forall_elim_vars_safe (no longer invents new indexes);
improved forall_elim_vars_safe (no longer invents new indexes);

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