This will allow for user feedback in main bip.log when an IRC error
occurs, like:
- 401 ERR_NOSUCHNICK
- 404 ERR_CANNOTSENDTOCHAN
- 432 ERR_ERRONEUSNICKNAME
These should not be logged as LOG_ERROR as they are not bip errors but
usually on the end user instead.
Signed-off-by: Loïc Gomez <bip@animanova.fr>