Make WaypointMgr to singleton.

Move global waypoint_map variable to WaypointMgr's private variable.

--HG--
branch : trunk

src/game/WaypointMovementGenerator.cpp

@@ -103,7 +103,7 @@ WaypointMovementGenerator<Creature>::Initialize(Creature &u)
     StopedByPlayer = false;
     if (!path_id)
         path_id = u.GetWaypointPath();
-    waypoints = WaypointMgr.GetPath(path_id);
+    waypoints = sWaypointMgr->GetPath(path_id);
     i_currentNode = 0;
     if (waypoints && waypoints->size())
     {