Minioning Intensifies

Adds the Vampire attack phase. Because of the backing models, any attacks
on Wolves or Hunters display as "Target is immune", but ultimately kill
the Vampire.
Healer saves!

Implements the healer class, and allows them to select a single player
to save once per game.
Minor visual tweaks

"Destined to die" players are now displayed as Yellow in the GameState
view

If the healer is unable to act, we now hide the button (it was displaying
through the image otherwise)