User documentation for file utils-gmp.H

This file defines a few very basic functions which I feel should really be part of the GMP library. Nevertheless I have placed all definitions inside the namespace CoCoA. Here is a summary:

• mpq_cmpabs(q1,q2) compare absolute values of rationals q1 and q2

• mpz_rounddiv(Q,N,D) -- compute Q = N/D where the quotient is rounded to an integer (currently halves round away from zero).

• mpq_round(N, Q) -- round rational Q to an integer; halves round the same way as in mpz_rounddiv

Maintainer documentation for file utils-gmp.H

The implementations are not exception safe. The emphasis was on obvious correctness rather than greatest speed.

Bugs, Shortcomings and other ideas

Currently mpz_rounddiv and mpq_round return a boolean saying whether the quotient was in fact an integer.