libpanel-applet: Add style class for orientation to PanelApplet
libpanel-applet: Add style class for orientation to PanelApplet

  Add style class "horizontal" or "vertical" based on the orientation
  of the PanelApplet. This allows themeing to adjust styling for vertical
  panels. An example selector would be:

  PanelApplet.vertical
  PanelApplet.vertical > GtkMenuBar.menubar {
    background-image: -gtk-gradient (linear, right top, left top,
                                     from (shade (@dark_bg_color, 1.15)),
                                     to (shade (@dark_bg_color, 0.95)));
  }

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>

https://bugzilla.gnome.org/show_bug.cgi?id=672070

GNOME/gnome-panel,GNOME/gnome-panel