Fixing error on client logoff: "Inventory: unable to remove 1 from <id>"

Everytime a client logs off, there is a debug message:
```
23:22:41 D Inventory: unable to remove 1 from 30002715.
23:22:41 D Inventory: unable to remove 1 from 30002715.
```
(the meaning is: the server tries to remove "EVE system" object with id 1 from some solar system)

This is caused by a bug in Inventory class that has RemoveItem method with uint32 argument, however SolarSystem class calls it with InventoryItemRef argument. This commit is to fix this by changing argument of RemoveItem to InventoryItemRef.

Also, it removes AttributeMap force update methods, because they are not needed anymore with that attribute map bug fixed.