 <li> <code>mpz_set_ui</code> and perhaps others like
          <code>mpz_tdiv_r_ui</code> and a prospective
          <code>mpz_set_ull</code> could be inlined.
     </ul>
<li> Add <code>mpf_out_raw</code> and <code>mpf_inp_raw</code>.  Make sure
     format is portable between 32-bit and 64-bit machines, and between
     little-endian and big-endian machines.  A format which MPFR can use too
     would be good.
<li> <code>mpn_and_n</code> ... <code>mpn_copyd</code>: Perhaps make the mpn
     logops and co