Inventory code implementation

[culacant]

Inventory scripting should be handled by an InventoryManager class.
This should contain a list of the items the player has, with the Id and amount of the item the player has in his inventory.
One item can be active/selected, think of keys to open doors. The bitmap for this item will show in the bottom-left corner of the screen.
If the player has a compass, this always shows a bitmap in the bottom-right corner of the screen.

The ITEMS.INI file contains the starting items, anything else will be handled by the map script.
The following functions need to be defined:

• HaveItem(id) < returns 1 if the player has the item in his inventory
• AddItem(id, amount) < adds amount of items to the inventory
• ActiveItem() < returns the Id of the currently selected item
• SelectItem(id) < sets the currently selected item
• DropItem(id, amount) < Removes an (amount of) item from the inventory
• DropAllItems() < same as DropItem but drops everything, used in catacombs when you lose everything
• UseItem(id) < if the item has a use_script set, this will spawn an RGScriptedObject to run that script.

Investigation backlog:

• ShowItem(id, UNKNOWN, UNKNOWN) < Same as inspecting item in the inventory; shows the 3D model an plays a sound
• ShowItemNoRtx(id, UNKNOWN, UNKNOWN, UNKNOWN) < identical to above but without the sound

Way-backlog:

• HandItem(id) < puts an item in the player's hand. Wielding stuff currently not implemented
• ItemUsed(id) < never used in the scripts
• PushItem(id, UNKNOWN) < never used
• PopItem(id) < never used
• SubItem(id, UNKNOWN) < never used
• PushAllItems(UNKNOWN) < never used
• PopAllItems() < never used
• RemoveItem(id) < never used