Doomsday Engine

Fixed|libcore|Scripting: Duplicating values with no ownership

Value::duplicateAsReference() was added so that values being duplicated
in expression evaluation do not cause inadvertently duplicated
Record instances. It defaults to Value::duplicate().

RecordValue::duplicate() will replicate the ownership relationship
in the duplicate copy, including a full duplicate of the owned record.
However, RecordValue::duplicateAsReference() will always reference
the original value's record.