Update (fix for DB)

Removed the demonbuddy reference for compiler options

Added tracking of backpack items during refreshing, which tracks occupied slots and stackable item IDs.
Added methods CanPickupItem and GetNumberFreeBackpackSlots to Backpack Class.
Item Pickup settings that enable all loot will now ignore checking quality of item
Item Balance Cache now updates plugin item type and base type as well as two slot and stackable properties.