adding an item manager

modified:   src/entity/npc/LivingEntityManager.java
modified:   src/environment/Map.java
modified:   src/environment/room/Room.java
modified:   src/environment/room/SpawnRoom.java
modified:   src/game/GameLoop.java
new file:   src/item/ItemManager.java
Merge branch 'master' into inventory
handling of the battery by the inventory
pressing f when carrying one drops it

modified:   src/entity/player/Player.java
modified:   src/environment/Map.java
modified:   src/environment/room/Room.java
modified:   src/event/control/PlayerControl.java
modified:   src/userInterface/inventory/Inventory.java
modified:   src/userInterface/inventory/InventoryItemEnum.java