- added inventory

- improved aiming with weapon

Inventory class manages UI which display all player items

InventoryUser class is transition class. ItemPicker picks weapon and uses InventoryUser to pass item to inventory. Also is used to put items that are on player on start.

InventoryContainerUI class display UI for items in conteiner when its open.

InventoryContainer class is put on any object and, by changing tag to 'Item', it can be used as item container - player can open UI and pick up items contained within.

InventoryContainer uses InventoryContainerUI to display its items.