[Usability] Changes to Epiphany following UI review

[Peter Harvey <peter a harvey gmail com>]

Hi all,

Following Monday's UI review we have committed most of the changes to
Epiphany. User interface changes include almost all those presented
prior to the review, plus some other minor items:
      * http://home.exetel.com.au/harvey/epiphany/toolbar/
      * An extra separator in the toolbar context menu when editing.
      * Use a regular expander widget for the topics palette.

String changes are:
      * Changed "Hide “%s”" to "Show “_%s”"
      * Changed "_Remove Toolbar" to "_Delete Toolbar"
      * Changed "_Show Toolbars" to "_Hide Toolbars"
      * Added an expander "Sho_w all topics"
      * Changed "Properties" to "_Properties"

Thanks,
Peter.