Properly handle broken pipe

In case of server side disconnection (crash/timeout/...),
ParaView now properly notify the user and provide a possibility to
save the current state to the disk.

Change-Id: I0555b45ef1624f1e157ddad922eb84d48eb96d2c
Add missing include for signals

Change-Id: Ie5776f45845611c529827c81b05a875684a9141e
fix warning observer for not used argument

Change-Id: I3345ff69747541f3cc2304393bd4cc3b5bef15ea
Merge topic 'better_disconnect_error_v2' into next

293f7ba fix warning observer for not used argument
fb9ad00 Add missing include for signals
45dd37f Properly handle broken pipe