Add :irc/notice message type

Signed-off-by: Moritz Ulrich <moritz@tarn-vedra.de>
Fix notification :sender for notices.

Signed-off-by: Moritz Ulrich <moritz@tarn-vedra.de>
Strip formatting in sauron handler.

Signed-off-by: Moritz Ulrich <moritz@tarn-vedra.de>