update Cartclass`s setCartItems()
add inventory class and getInventoryText()
add promotionItem class extends Item
add promotionItem class,at cartclass add get,setPromotionItems()
at inventory class add setsetCartItemsText()
at inventory class add get,setPromotionsText()
update bug
at inventory add set,getTotalPrices()
at inventtory class add set,getPromotionPrice()
update promotionItem class bug
Complete printIncentory()
add date handling