Handle SIGTERM, SIGHUP signals

Attempt to shutdown gracefully on receiving SIGTERM or SIGHUP from another process. This allows to properly save the conversation history.

Ref. isamert#112

scli

@@ -15,6 +15,7 @@ import pprint
 import re
 import shlex
 import shutil
+import signal as signal_ipc
 import subprocess
 import sys
 import tempfile
@@ -4431,6 +4432,9 @@ def main():
         atexit.register(proc.kill)
         action_request.set_status_line("Initializing signal-cli daemon... ")
 
+    for sig in {signal_ipc.SIGHUP, signal_ipc.SIGTERM}:
+        signal_ipc.signal(sig, lambda signum, frame: action_request.quit())
+
     with BracketedPasteMode():
         loop.run()