Asynchronous PRNG (and .gen() method)

[1valdis]

I want to use an async function to generate cryptographically strong random numbers for Randexp. But seems like currently randexp.randInt can only return generated value, not a Promise of the value. It would be good to see that implemented so that I can generate cryptographically strong passwords and tokens according to regular expressions. Although making that possible probably also means making .gen() function async too...