[WIP] Undo

Just for tracking purposes.

### Todo

- [x] Transform stacks when remote operations are applied
- [x] Isolate and fix Undo + Redo bug.
- [ ] Compose multiple edits into chunks.


### Demo

```bash
$ npm install
$ cd prototype
$ npm install
$ node server.js
$ open localhost:7007
```

**undo** `Ctrl+Z` 
**redo** `Ctrl+Shift+Z`