
- Examine behavior near 32-bit limit on 32-bit machines.
  (done for factoring)

- GMP versions of all routines.

- segment sieve should itself use a segment for its primes.
  Today we'd need sqrt(2^64) max = 140MB.  Segmenting would yield under 1MB.

- Add test to check maxbits in compiled library vs. Perl

- Li(n)

- Pure perl implementations

- input validation (in XS, or do we need to make Perl wrappers for everything?)

- Faster SQUFOF

- nth_prime bounds are < in the code, but <= in the documentation.

- speed up random_prime for large numbers
