 nice if it worked for plain <code>int</code> etc too, not just
     <code>mpz_t</code> etc.
<li> <code>gmp_printf</code> in fact could usefully accept an arbitrary base,
     for both integer and float conversions.  A base either in the format
     string or as a parameter with <code>*</code> should be allowed.  Maybe
     <code>&amp;13b</code> (b for base) or something like that.
<li> <code>gmp_printf</code> could perhaps accept <code>mpq_t</code> for float
     conversions, eg. <code>"%.4Qf"</code>.  Thi