* Reinstate the GUI.
  * Remove 19-disable-gtk-config-interface.diff.
  * 19-update-config-interface-to-gtk2.diff: New patch, port GUI to GTK+ 2.
    (Closes: #511953)
  * 09-dont-set-gtk-locale.diff: Change to setting C locale explicitly,
    since GTK+ 2 sets locale unconditionally. Rename to 09-set-c-locale.diff.
  * Build-depend on libgtk2.0-dev.
  * Add Recommends on libgtk2.0-0.
* Change build-dependency from outdated package from xlibmesa-gl-dev to
  libgl1-mesa-dev.