Really reproducible random #276
Description
We have class ReproducibleRandom which leaves a lot to be desired. In particular, reproducibility across all the platforms and runtime versions.
I suggest let's implement our own Random. They say Dr. Knuth offered a very good explanation of one implementation in his books; perhaps worth taking a look?
We can get an implementation from a library, but I am not sure it will give us required guarantees on reproducibility (I do not want it to change across library versions or, like_ ever_; even if we introduce new ways to work with Random, we should keep compatibility with old replays by keeping old versions as necessary, unless we have a very solid reason to break it).