Store "transactions" to enable undo/redo history

[NullVoxPopuli]

Kind of based off of the data structure in #144

It could be good to record "transactions" every time execute is called, effectively storing that current/original object from #144 as a type-of-snapshot each time execute is called. Or maybe it'd look like:

changeset.transactions
// returns =>
[
  {
    executedAt: timestamp,
    snapshot: (existing snapshot)
    changes: {
      key: { original, current }
    }
  },
    {
    executedAt: timestamp,
    snapshot: (existing snapshot)
    changes: {
      key: { original, current }
    }
  }
  // ....
]

This would enable undo/redo history

[snewcomer]

Also in favor of this as well 👍