Table of contents revealed via swipe instead of drag.

For now performance was too poor on iOS 6 to redraw
continuously during drag event.

TOC drag disabled if there's no article loaded yet.

Pull to refresh disabled if there's no article loaded.

History, saved pages, search results and language picker
no longer use blue table cell selection color on iOS 6.

Change-Id: I67175f141902193c1290cc1307dabb5d14152c74