Support Cycle.js Diversity

[TylorS]

Add support for the next version of Cycle.js which is stream agnostic. Possibly porting to xstream (as the other core drivers are doing) or possibly in a stream agnostic fashion like the history driver.

[aravantv]

+1!

[jsamr]

+1

[Widdershin]

Good news on this front, the xstream release of cycle-restart is almost ready! That means this issue will soon be able to move forward.

I think as part of the next step in cycle-time-travel ideally we would first address cyclejs/cyclejs#380.

Having a unified source of truth for time in Cycle applications would make both restart and time-travel much easier to implement.

[mjyc]

I updated the code in this repo to work with the latest release of cycle.js modules: https://github.com/mjyc/cycle-time-travel

I noticed there were some work regarding #17 but is there interest in migrating to the latest cycle.js as-is?

[Widdershin]

@mjyc yep if you want to open a PR I'd love to merge it.

There's another piece of work that needs to happen before #17 is legitimately possible, which is that the stream graph changes over time. @staltz and I knocked around a few solutions for that a while ago but never got around to actually solving it.