Core/Vehicles: temp fix visibility issues when creatures enter a vehicle, this also fixes the 'Ride Vehicle' type spells

note: isntance scripts using spell+EnterVehicle() hacks should be updated

--HG--
branch : trunk

src/server/game/Entities/Vehicle/Vehicle.cpp

@@ -353,6 +353,8 @@ bool Vehicle::AddPassenger(Unit *unit, int8 seatId)
             RelocatePassengers(me->GetPositionX(), me->GetPositionY(), me->GetPositionZ(), me->GetOrientation());
         }
     }
+    unit->DestroyForNearbyPlayers();
+    unit->UpdateObjectVisibility(false);
 
     if (GetBase()->GetTypeId() == TYPEID_UNIT)
         sScriptMgr.OnAddPassenger(this, unit, seatId);