Varible session_state moved to global namespace

The variable session_state, defined in screen.h (WScreen), is moved to
the global variable w_global.

Signed-off-by: Rodolfo García Peñas (kix) <kix@kix.es>

src/WindowMaker.h

@@ -560,6 +560,9 @@ extern struct wmaker_global_variables {
 		XContext stack;
 	} context;
 
+	/* Session related */
+	WMPropList *session_state;
+
 	/* Application related */
 	struct WAppIcon *app_icon_list;	/* list of all aplication icons */