PidginSnarl: have maximum number of notifications at one time
Right now, when logging into Pidgin the screen will fill completely with notices entered in a continuous chat. This interferes with other windows for a significant amount of time. It seems the only way to prevent this is putting Snarl into Do Not Disturb mode on startup (or not having it start automatically at all). Limiting the number of PidginSnarl notifications displayed at once would solve the problem.