use "_moz_mailbeep". on windows, we map this to "MailBeep" (so it works on win2k and win98)
and on mac we use sfraser's code to go to internet config. (nothing on linux yet, that's another bug)
r=pinkerton, sr=sfraser
also, fix#104252. selectively notify folder listeners. when we register the folder listener
with the mail session, we pass in flags for what types of things we care about.
this reduces the notifications, especially those across XPConnect.
r=bienvenu, sr=mscott
git-svn-id: svn://10.0.0.236/trunk@105195 18797224-902f-48f8-a5cc-f745e15eee43
09f92b7807