When we don't have a matching card for the lead card rather than
always preferring to play hearts we should try to get rid of our
high value cards first if no other player has hearts cards higher
than what we have.
Previously the AI would prefer playing a lead card for which no other
player had a card with a higher value even though it also had a card
for which a higher value card was still in play.
Instead of picking the card with the lowest value we should pick the
card with the highest value for which we know no lower value card is
in play anymore and that someone else still has an even higher value
card.
