Use filters for playersAlive and playersDead

I planned when writing the player that the player.alive boolean would be
updated when a player dies, then forgot about it.

Now, we have a list of allPlayers. state.playersAlive is simply a filtered
version of allPlayers. Killing a player only means setting player.alive = NO,
and the lists update themselves.
Add table of players

Adds a table listing all player names, roles, and coloured to indicate
whether the player is alive (green) or dead (red).

Also made all the backgrounds black, to fit the "dark" theme of the game