Improve keyboard support for drawers.

- Give keyboard focus to history or station list when showing the drawer (or reselecting "show" when the drawer is already visible).

- Bind the return key to start playback of the selected station (equivalent to the play button).
Use standard list highlight colors for history.
Set history item sizes - makes truncation work properly.
Don't highlight the album art in history when clicking on it.
Merge pull request #145 from nriley/drawers

Drawers