Fixed seed for the stream

[LostKobrakai]

For an application of mine I'd like to keep the same colors per section, so that e.g. a reload won't result in different colors being presented.

[nickveys]

Good idea, I'll take a look at adding that.

[nickveys]

If you were to send a fixed (but most likely different) set of initial values for each stream instance, you should get deterministic results. Otherwise, since these are random and based on a seed that is stored in the current process, this would need to be modified to have one stream per-process and set the seed in that process before starting the streaming values.

If you want to take a crack at it and send a PR, this article seems to have a reasonable approach described (http://learningelixir.joekain.com/stream-patterns-in-elixir-3/). Otherwise I'm not sure when I'd be able to get around to it myself.