Fixed: missing stdpch.h (fixes #303)

--HG--
branch : develop

code/ryzom/client/src/item_group_manager.cpp

@@ -13,6 +13,9 @@
 //
 // You should have received a copy of the GNU Affero General Public License
 // along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+#include "stdpch.h"
+
 #include "item_group_manager.h"
 #include "interface_v3/inventory_manager.h"
 #include "nel/gui/widget_manager.h"