Sell feature added! Upgrade button renamed to Sell/Upgrade, and here you can now sell unwanted cards. Common, Uncommon, Rare, Very Rare, sell for 1,3,15,20 gold. Upgraded cards sell for 5 times that value. Upgraded Pillars and Pends sell for 25 and Marks and Nymphs are unsellable.
Also, I changed the button mouseover/clicked graphics, because it is horrible to work with 3 seperate sprite sheets. Now it's just one sheet, and the effects are done in code. Not as good-looking maybe, but that can be changed later on.