Spawning actors with a reliable network

[jeffa5]

Currently, actors can be spawned with UDP connections, though we may model them with reliable ordered networks.

It would be cool to be able to spawn the actors with TCP connections to have this be more accurate.

[jonnadal]

@jeffa5 before adding TCP I was inclined to introduce persistence and modeling of actor restarts. That would allow me to update ordered_reliable_link to maintain its invariants between actor restarts and (coming back to this proposal) TCP session restarts (as nothing guarantees ordering across sessions). But that's not an argument against introducing TCP earlier; just sharing how I was thinking about these.

[jeffa5]

That sounds good, actor restarts are one of the things I ended up using named timers for.