Secrets of Toanium

Where it stands right now, each card or Enviro is made separately and then collected into a deck. This is wasteful both in content production time, as the same background image must be downloaded repeatedly, and of compute resources as we now have a separate copy of the same background image, one for each card.

We could use "copy" in the card editor to do this, but I think a smoother, more intuitive process would be for the deck editor to spawn/return a card editor with the deck and background already selected.