Keyboard Navigation

[b-camphart]

From #13 Allow arrow keys, or perhaps even vim bindings, to navigate through items in the timeline.

Questions:

• if there are a lot of items with the same value and thus the "next" item is below the previous, should the "next" key navigate to the item below, or one off to the side?

[b-camphart]

Current solution:

• can use the tab key to navigate through items (arrow keys scroll the timeline)
• right-click to focus on a specific item