Add trade history and "Undo" feature

[w0rp]

You can easily make mistakes with trades in the UI, and it can be hard to see the difference before you take action. It is desirable to store a history of all past trades made, and add an "undo" action that reverse previous trades so you can quickly make a change, see the change in action, and then "undo" that change to go back again.

It might be a good idea to preserve the history of actions for a long time so you can "undo" and then "redo" actions from even days ago.