Empty timeline when using save/open from non-timeline screen

[wwqrd]

To replicate the Empty timeline issue in Architect:

1. Open a protocol
2. Click on a stage within that protocol
3. Then do one of two options: (a) either "Save As" a new file, or (b) in file explorer double click to open a different protocol
4. Click the "Close" button to leave the stage
5. You'll see an empty timeline at this point.
6. Return to start screen and select the protocol again, and timeline is populated correctly.

Also:

• When opening from the menu.

There are 2 things happening:

• The app is attempting to go back in history when the screen is closed, but the history is reset when the protocol is saved/opened, so it's attempting to go back to a non-existent point. The timeline middleware shouldn't allow this.
• There is no kind of warning or confirmation of what is going on, if the user has on-going changes on the screen they are lost with no warning. This needs a rethink.

fix/history includes a fix for the timeline middleware.