added is_const/declare_const for local scope of fixes/consts;
added is_const/declare_const for local scope of fixes/consts;

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