+ refactored code
+ improved card border lines (black)
+ cards no longer have curved edges, this prevents card image corners
showing behind.
+ tapped cards now have better border lines

Drop CardInfo’s own pixmap caches; use QPixmapCache instead.
Use QPixmap references instead of pointers.
Being stored in QPixmapCache, all card images are now subjected to
QPixmapCache’s size limit

Cards now scale up by 10% when mouse over.