[fwtczjqv] Navigating Undo and Redo

As you keep hitting "Undo", you will hit a branch point, whether to go to the state immediately backwards in time, or to the state which is the predecessor to the current state, which might be a long jump backwards in time, perhaps skipping over a long abandoned edit.  Fortunately, undos have maximum branching factor two.

Analogously, "Redo" you can simply go forward in time, or to the potentially many children of the current state.

Create an UI for navigating Undo state like this.  Being able to name and describe "branches" will be useful; name a to-be-aborted branch just before hitting undo.  Automatically generate a useful branch name summarizing the change in it (AI). Of course, time stamps.