Generates random numbers using Wyrand algorithm (which is not
cryptographically secure, but ostensibly passes some popular tests — I didn't
verify that).

No unsafe, no dependencies other than std (except on WASM, where it pulls
in instant crate to get initial entropy).

By default, the generator is initialized from a hash of
std::time::Instant::now() and process ID. Good enough for a non-cryptographic
PRNG.

Interesting detail: if the thread-local storage has already been
de-initialized by we try to use it, the generator is initialized by a fixed
seed 0x4d595df4d0f33173. This constant is an initial state for PCG-XSH-RR,
which is an algorithm that previous versions of the crate used.

I verified that the algorithms match the documents they reference:

• Wyrand implementation matches wyrand() in
  https://github.com/wangyi-fudan/wyhash/blob/master/wyhash.h at commit
  399078afad15f65ec86836e1c3b0a103d178f15b
• random shuffling matches
  https://lemire.me/blog/2016/06/30/fast-random-shuffling/
• 128-bit multiplication matches
  https://stackoverflow.com/questions/28868367/getting-the-high-part-of-64-bit-integer-multiplication/28904636#28904636

I also verified that the algorithms that generate floating-point numbers
indeed do what they're supposed to do: set sign to 0 (i.e. positive),
exponent to 127 (i.e. zero), then fill the fraction with random bits, and
subtracting 1.0 from the result to get [0; 1).

Also worth mentioning that the crate doesn't guarantee a specific algorithm,
so you shouldn't depend on a specific seed to always produce the same
results.

Recommended for non-cryptographic purposes that do not require
reproducibility.

Generates random numbers using Wyrand algorithm (which is not
cryptographically secure, but ostensibly passes some popular tests — I didn't
verify that).

No unsafe, no dependencies other than std (except on WASM, where it pulls
in instant crate to get initial entropy).

By default, the generator is initialized from a hash of
std::time::Instant::now() and process ID. Good enough for a non-cryptographic
PRNG.

Interesting detail: if the thread-local storage has already been
de-initialized by we try to use it, the generator is initialized by a fixed
seed 0x4d595df4d0f33173. This constant is an initial state for PCG-XSH-RR,
which is an algorithm that previous versions of the crate used.

I verified that the algorithms match the documents they reference:

• Wyrand implementation matches wyrand() in
  https://github.com/wangyi-fudan/wyhash/blob/master/wyhash.h at commit
  399078afad15f65ec86836e1c3b0a103d178f15b
• random shuffling matches
  https://lemire.me/blog/2016/06/30/fast-random-shuffling/
• 128-bit multiplication matches
  https://stackoverflow.com/questions/28868367/getting-the-high-part-of-64-bit-integer-multiplication/28904636#28904636

I also verified that the algorithms that generate floating-point numbers
indeed do what they're supposed to do: set sign to 0 (i.e. positive),
exponent to 127 (i.e. zero), then fill the fraction with random bits, and
subtracting 1.0 from the result to get [0; 1).

Also worth mentioning that the crate doesn't guarantee a specific algorithm,
so you shouldn't depend on a specific seed to always produce the same
results.

Recommended for non-cryptographic purposes that do not require
reproducibility.