Builds an Item's GUID.
Item GUID consist of low GUID and type ID
Player and Item for example can have the same low GUID but not GUID.
guid = GetItemGUID( lowguid )
number lowguid
Low GUID of the Item.
Valid numbers: integers from 0 to 4,294,967,295.
number guid
Valid numbers: integers from 0 to 18,446,744,073,709,551,615.