tuned conversion from terms to "polynomials" for arith_tac: takes care of "uminus" now.
tuned conversion from terms to "polynomials" for arith_tac: takes care
of "uminus" now.

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