Make WaypointMgr to singleton.

Move global waypoint_map variable to WaypointMgr's private variable.

--HG--
branch : trunk

src/game/Level2.cpp

@@ -2433,7 +2433,7 @@ bool ChatHandler::HandleReloadAllPaths(const char* args)
         return false;
 
     PSendSysMessage("%s%s|r|cff00ffff%u|r", "|cff00ff00", "Loading Path: ", id);
-    WaypointMgr.UpdatePath(id);
+    sWaypointMgr->UpdatePath(id);
     return true;
 }