Squashed 'deps/rust-bignum/' changes from 7be0537..371d543

371d543 Partial BigInt implementation, modulus, and from_str_radix
5fd96c7 Don't build deps constantly
411b9e9 Merge commit 'e546436be4fa225998c2ef41f5f223e1d90b4ead'
e546436 Squashed 'deps/rust-gmp/' changes from a0544cc..5e7542a

git-subtree-dir: deps/rust-bignum
git-subtree-split: 371d5434d0dcd774b916b27d459849ffb468dc95
Merge commit '4025ff0ec933aca9c363a34dabc66b27b0e43405'
Make the deps of deps, but not all the time, pass test args
Add RSA implementation

Break existing prime number functions into their own module.

Encrypting and decrypting work! So it has that going for it. Even if it
is rather ugly and sloppy.