- The ERR_NOCTRLSONCHAN and ERR_NOCTCP numerics have been dropped. Whenever a message
  cannot be sent to a channel, ERR_CANNOTSENDTOCHAN is returned with the according
  reason.
- KNOCK can now be used on private channels. Channel mode +K can be used instead to control
  whether or not KNOCKs may be used on a channel.