[FIX] im: notifications fixes & sound change

notification sound on first message of conversation
no notification when message received is from the current uid
notifcation sound changed. Louder & clearer.
[FIX] im: open url in another tab/window
[FIX] im: notification sound change
[FIX] im: add fnct search to im_status to search connected users

search display connected users before discconnected users