NHT: Keyboard shortcuts to add stats

[josh-bitovi]

This still needs to be defined. Work with power users to figure out what these should be. Some starting suggestions:

• j and k or ↑ and ↓ to nav through lists
• Make a non-<option>-based list for stat type so it can be moved through with j and k?
• Ensure tabbing through form controls works as expected and is intuitive (tabindex?)
• Possibly add specific keybindings per-stat? Maybe not though... simply fixing tabbing through UI elements and moving up and down lists may be enough

[josh-bitovi]

Let's use mousetrap

[josh-bitovi]

Suggestion for seeking:

• h and l (lowercase L) and ← and →: seek back/forward 2s
• H and L and Shift-← and Shift-→: seek back/forward 5s (Note: Shift-arrow may already be taken by the browser?)