[haXe] cross-platform pseudorandom numbers

[jhofmann at 321f.net]

For my current project, I will need a way to generate pseudorandom numbers
in pure haXe. The project is a Flash game, which records the game and then
uploads it to a NekoVM server: the server replays the game and validates
the score to prevent hacking the scoreboard. The existing standard library
is not good enough for this as it does not allow me to guarantee the
predictability of gameplay - the RNG on different platforms varies.

Has anyone looked into this before? Any suggestions? I suspect I will have
to implement something myself...