Mark decks with unimplemented cards as something other than 'valid'

[EBaalhuis]

The feature that checks whether decks are valid does not take into account unimplemented cards, or unreleased cards. For example, currently the Lion clan pack is neither released officially nor implemented, but decks that contain cards from it are still marked valid. This is confusing for users making a deck and can cause games to come to an early end when it turns out a card is not implemented (and hard/impossible to resolve manually).