This is an interesting module, from what it looks like the `IsaacRng` implementation was copied from where it was before, and `Isaac64Rng` was implemented in this pull request. I've got a few questions about this:

* I'm unfamiliar with this area, but do you know if this is one of those crypto-areas where "you shouldn't roll your own"? If it's generally bad practice to re-implement these algorithms, it seems like a bad idea for us to be doing this as well.

* Are the canonical names for the 32 and 64 bit variants `Isaac` and `Isaac64`? I'd almost rather have `Isaac32` if that's not the case.

* Assuming that you translated implemented `Isaac64`, did you just copy the implementation of `Isaac` and change the constants?