Implement stealth attribute
Implement most warlock spells
Implement an Entity.isDamaged() helper
Fix Claw and Bite
Implement most remaining warrior spells
Finish implementing non-Choose One druid spells
Move secret logic to a new Secret class
Rewrite the summon/play player/card chain

- Player.play(card) now plays a card from the Player's hand.
- Player.summon(card) plays an arbitrary card for the Player
- Card.play() is a helper for Player.play(card)
- Card.summon() handles the class-specific card summoning logic
- Card.activate() will trigger the activate script from the card data
- Entity.buff() now summon()s an Enchantment
- Hero Powers are now properly "played" through activate() and summoned
  through play() or summon()
Implement overload
Default to 1 spellpower if entity has the Spellpower tag
Implement most Shaman minions
Correctly destroy secrets
Implement more Hunter spells
Do the seed-dependant tests early on
Use a custom CardList instead of a list() where relevant
Implement Minion.adjacentMinions with some tests
Implement XMLCard.adjacentBuff
Use Enchantment.summon(card) to implement Card.buff()
Rename owner to controller
Implement adjacent auras