3f9e6a7be5
Using a virtual base class DeckItem that exposed DeckInt/Double/String types means it cannot be held in a vector and managed automatically without unique_ptr, which is clunky and makes iterator aliases impossible. This patch moves the unique_ptr details into DeckItem which now behaves as if it was virtual, except it only forwards calls to its inner, managed object (much like private implementation). This gives the benefit of automatic/stack allocation, and no particular drawback aside from slightly less obvious implementation. Clients can still call get< int > on a DeckItem::double, but that was also possible with the virtual solution (i.e. nothing lost).