crdt.Row is now a delta stream and a scuttlebutt instance

Most of it is just API changes.

The only painpoint is the `hasKey` stuff in `crdt.Set`

This is needed because deltas trickle in one key/value pair at a time and the key/value pair isn't set initially.

I did a shit ton of debugging and testing to make sure all the examples & tests still pass (they do).

The added complexity in `crdt.Set` is a pain, suggestions on how to refactor that would be appreciated.