daemon: allow client to be notified when the peer's daemon is terminated before the call is ended
Issue generated from Tuleap's migration script. Originally submitted by: Andreas Traczyk (andreas.traczyk)
During a call, if one of the peers abruptly disconnects, the other peers should be made aware of this, and the respective call should be terminated. Abrupt disconnections can be caused in variety of ways on various platforms including: ctd, kill signal, End Task (Windows), ACPI shutdown, etc.