added rev_order, make_ord; reimplemented sort function: stable version of quicksort;
added rev_order, make_ord;
reimplemented sort function: stable version of quicksort;

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