RNG seeding using crypto/rand uint64

[qdm12]

• To rebase once #1, #2 and #3 are merged.
• It was taking 127ns before it now takes 550ns but this is only done once per RNG
• I think this is very much reasonable as no user would create a very large number (billions+) of goroutines. And it allows our RNGs to be seeded properly 👍