[Suggestion] mark holiday items as a distinct set

With AotA's introduction of the "set" field in Equipment.csv, it is now possible to distinguish the holiday items by a unique set identifier (aside from merely being tagged as undroppable). It's probably not worth creating a separate set identifier for each holiday, so they could all use the same set id (probably "2").

I suppose the keep/store filter would be something like "Promo", or maybe "LE" (Limited Edition). (Is there some other CCG lingo for special event cards?)

 

Promo, yeah.
Flax's could be included

 

Or not as it can be dropped at any time.