introduce GRemoteActionGroup

This interfaceifies the extra functions that were on GDBusActionGroup
for dealing with platform data.

The two main benefits of doing this:

  - no longer have to do a silly song and dance in GApplication to avoid
    calling GDBusActionGroup API from non-dbus-aware code

  - the interface can be reused by the action group exporter to avoid
    ugly and unbindable hook callbacks

https://bugzilla.gnome.org/show_bug.cgi?id=665737

docs/reference/gio/gio-sections.txt

@@ -2940,6 +2940,22 @@ G_DBUS_ACTION_GROUP_GET_CLASS
 g_dbus_action_group_get_type
 </SECTION>
 
+<SECTION>
+<FILE>gremoteactiongroup</FILE>
+GRemoteActionGroup
+GRemoteActionGroupInterface
+
+<SUBSECTION>
+g_remote_action_group_activate_action_full
+g_remote_action_group_change_action_state_full
+
+<SUBSECTION Standard>
+G_TYPE_REMOTE_ACTION_GROUP
+G_REMOTE_ACTION_GROUP
+G_IS_REMOTE_ACTION_GROUP
+G_REMOTE_ACTION_GROUP_GET_IFACE
+</SECTION>
+
 <SECTION>
 <FILE>gaction</FILE>
 <TITLE>GAction</TITLE>