renamed miaou.notify to make it clearer it doesn't manage all notifications but only desktop ones
refactoring notif things to the notif module
all pings are now manually acquitted by user, sent to all rooms and removed in all rooms
Merge branch 'master' into pinglist
Fixed a failure to launch for users not having allowed desktop notifications.

Code in miaou.horn was directly executed at module initialization and called the module md. Being concatenated before md, it made it call an empty module.
I fixed that by calling the initialization of horn from chat init (as for other modules).
stop propagation on message buttons (reply, delete, etc.) to prevent wzin freezing
change email max size (in DB) to 254 chars instead of 150
fixed a bug preventing notifications handling