Timetravel dropdown should be reversed

[ianjennings]

Right now the timetravel dropdown looks like this:

• output [next]
  • oldest transition
  • newest transition

After playing with it, I think it should look like this:

• [prev] output
  • newest transition
  • oldest transition

This way the order and buttons make sense. What you see is the latest, and as you navigate you go "back in time"

[ianjennings]

Oh, while you're here, Source Output should prob just be output.

[ianjennings]

If you're fancy, when the dropdown is open the current position should be highlighted.