- add card type to CTCardTrader: Tell the card trader what kind of card we
  are waiting for (by name, such as "HBCICard")
- let the card trader return a special card type (e.g. when waiting for a
  HBCI card then a CTPointer to a HBCICard object should be returned.
- add CTCard::checkCard (which does what reopenCard did) [maybe]