Implement additional IntInf operations using GMP.

[MatthewFluet]

There are a number of number theoretic functions implemented by GMP that would be beneficial to implement and expose as MLton.IntInf.* functions. In particular, lcm (least common multiple) would be useful to implement.

[rcythr]

Although all of these functions are probably useful for some users, it is worth mentioning that for every additional function we add here the scope of #60 increases.

That said, I did some analysis and work on this item to familiarize myself with the codebase. My current change on feature/extra_gmp_functions adds support for lcm so far.

Here are the other functions that jumped out to me as being interesting. Bolded functions can reuse the GC helper functions IntInf_binop or IntInf_unop, and are the easiest to implement:

From Number Theoretic

• mpz_probab_prime_p
• mpz_nextprime
• mpz_jacobi
• mpz_legendre
• mpz_kronecker
• mpz_remove

From Integer Roots

• mpz_root
• mpz_rootrem
• mpz_sqrt
• mpz_sqrtrem
• mpz_perfect_power_p
• mpz_perfect_square_p

Should we add the above functions, a subset of the above functions, or just lcm?

[MatthewFluet]

I think those that can reuse existing helper functions should be straightforward to add. And then maybe also the predicate (_p) functions.