`modfctr'
---------

modfctr(POLY,MOD)
     :: Factorizer over small finite fields

RETURN
     list

POLY
     Polynomial with integer coefficients

MOD
     non-negative integer

   * This function factorizes a polynomial POLY over the finite prime
     field of characteristic MOD, where MOD must be smaller than 2^29.

   * The result is represented by a list, whose elements are a pair
     represented as

     [[num,1],[factor,multiplicity],...].

   * Products of all factor^multiplicity and num is equal to POLY.

   * To factorize polynomials over large finite fields, use `fctr_ff'
     (*note Finite fields::,*Note fctr_ff::).

     [0] modfctr(x^10+x^2+1,2147483647);
     [[1,1],[x+1513477736,1],[x+2055628767,1],[x+91854880,1],
     [x+634005911,1],[x+1513477735,1],[x+634005912,1],
     [x^4+1759639395*x^2+2045307031,1]]
     [1] modfctr(2*x^6+(y^2+z*y)*x^4+2*z*y^3*x^2+(2*z^2*y^2+z^3*y)*x+z^4,3);
     [[2,1],[2*x^3+z*y*x+z^2,1],[2*x^3+y^2*x+2*z^2,1]]

References
     *Note `fctr sqfr': fctr sqfr.

