- code review and fix the old race condition in dev->set_multicast_list
 - use tq_schedule instead of tq_immediate
 - remove card_num and dev_num from struct dvb_net (now obsolete)
 - prevent interface from being removed while it is in use
 - allow add/remove only for the superuser
 - set check-CRC flag on section filter to drop broken packets
 - some more debug printfs in filter handling code
 - cleaned up and commented packet reception handler
 - fix formatting