* Improve rand(bool)
* Use sign test instead of mod 2
* Use mod 2 again, as it works for js
* Use right shift as suggested by the authors of xoroshiro
* Update random.nim
* General case doesn't need any right shift it was correct to begin with
* Update random.nim
* add comment
Co-authored-by: flywind <43030857+xflywind@users.noreply.github.com>