gtkplacesidebar: use GtkListBox

We were using GTkTreeView in a simple list. Also, as we know,
GtkCellRenderers are not the best way to theme and manipulate
widgets.

So instead use a GtkListBox to modernize the GtkPlacesSidebar,
and in the way clean up some parts of the code (like headings)
which were not used anymore.
Also we don't use a model anymore, since the data is simple
enough to manage it in a subclass of the row itself.

gtk/gtkplacessidebarprivate.h

@@ -0,0 +1,54 @@
+/* gtkplacessidebarprivate.h
+ *
+ * Copyright (C) 2015 Red Hat
+ *
+ * This file is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU Lesser General Public License as
+ * published by the Free Software Foundation; either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This file is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Authors: Carlos Soriano <csoriano@gnome.org>
+ */
+
+#ifndef __GTK_PLACES_SIDEBAR_PRIVATE_H__
+#define __GTK_PLACES_SIDEBAR_PRIVATE_H__
+
+#include <glib.h>
+
+G_BEGIN_DECLS
+
+/* Keep order, since it's used for the sort functions */
+typedef enum {
+  SECTION_INVALID,
+  SECTION_COMPUTER,
+  SECTION_DEVICES,
+  SECTION_NETWORK,
+  SECTION_BOOKMARKS,
+  N_SECTIONS
+} GtkPlacesSidebarSectionType;
+
+typedef enum {
+  PLACES_INVALID,
+  PLACES_BUILT_IN,
+  PLACES_XDG_DIR,
+  PLACES_MOUNTED_VOLUME,
+  PLACES_BOOKMARK,
+  PLACES_HEADING,
+  PLACES_CONNECT_TO_SERVER,
+  PLACES_ENTER_LOCATION,
+  PLACES_DROP_FEEDBACK,
+  PLACES_BOOKMARK_PLACEHOLDER,
+  N_PLACES
+} GtkPlacesSidebarPlaceType;
+
+G_END_DECLS
+
+#endif /* __GTK_PLACES_SIDEBAR_PRIVATE_H__ */