 <code>scan1</code>.
     Suggested by Roberto Bagnara.
<li> <code>mpz_bit_subset</code> or some such to test whether one integer is a
     bitwise subset of another might be of use.  Some sort of return value
     indicating whether it's a proper or non-proper subset would be good and
     wouldn't cost anything in the implementation.  Suggested by Roberto
     Bagnara.
<li> <code>mpf_get_ld</code>, <code>mpf_set_ld</code>: Conversions between
     <code>mpf_t</code> and <code>long double</code>, suggested