`dp_dtop'
---------

dp_dtop(DPOLY,VLIST)
     :: Converts a distributed polynomial into an ordinary polynomial.

RETURN
     polynomial

DPOLY
     distributed polynomial

VLIST
     list

   * This function converts a distributed polynomial into an ordinary
     polynomial according to a list of indeterminates VLIST.

   * VLIST is such a list that its length coincides with the number of
     variables of DPOLY.

     [53] T=dp_ptod((x+y+z)^2,[x,y]);
     (1)*<<2,0>>+(2)*<<1,1>>+(1)*<<0,2>>+(2*z)*<<1,0>>+(2*z)*<<0,1>>
     +(z^2)*<<0,0>>
     [54] P=dp_dtop(T,[a,b]);
     z^2+(2*a+2*b)*z+a^2+2*b*a+b^2

