Change soapboxes for future winter events

[srmalloy]

With the accidental change to the soapbox texture that various mobs stand on, and the winter event changing all thrown objects to presents (making some fights look like Santa's sleigh exploded overhead), it occurs to me that there's an opportunity to add some amusement to the event -- change the soapboxes out for presents. Since so many hero fights will leave discarded present boxes lying around, it's reasonable for NPCs to snag one if they need a box to stand on when orating.