tutor.set: use text spoiler to remove pagination

This change has two downsides:

  - the "versions" attribute now provides less detail, and
  - tutor.card and tutor.set now present "versions" differently.

Before:

    140233:
      expansion: "Lorwyn"
      rarity: "Rare"
    191239:
      expansion: "Magic 2010"
      rarity: "Mythic Rare"
    205957:
      expansion: "Magic 2011"
      rarity: "Mythic Rare"

After:

    "Lorwyn": ["Rare"]
    "Magic 2010": ["Mythic Rare"]
    "Magic 2011": ["Mythic Rare"]