Bounty: Privacy relay usage

Explore ways to modify `REQ|EVENT` commands so that relays don't gain as much information about clients' behavior.

Right now all relays a user is connected to get all commands from that user, so it's trivial for a user to observe what that user is doing, who the user is stalking and generally profile all the user's activity.

We need to add a relay-privacy algorithm to the command routing to route commands to relays in a way that still has enough possibilities of finding the required information but that it lowers the amount of information relays gain from the user.