Automatically delete basket after inactivity period

[pReya]

Many people might try out the system or touch the screen without purpose. So, if no touch/rfid events happen for a period of X seconds, the basket should be purged and the system should return to the main screen.

[ofosos]

We already discussed something like this. We need a resettable time and an event stream filter for Qt to make this happen. It should not be that hard, especially since we moved most of the event processing for the RFID events into the Stack instance. This handler would go into the same place.