Bug fix release.

Per-site settings work now. Nocturne could not tell which site you were on, so the site name, the on/off switch and the per-site sliders all did nothing, the toolbar icon never showed it was on, and the per-site keyboard shortcut did nothing either.

Also fixed:

• Pages no longer drift towards flat grey a second after they load.
• A site you switch off can be switched back on.
• "Site theme only" no longer recolours a site you have visited before.
• A change in the popup no longer undoes one made in the settings page.
• With "Stubborn sites" on, switching Nocturne off now really switches it off.
• The schedule time fields are labelled for screen readers.