History: Trap some external signals, try to quit gracefully
Closes #3 (closed).
This traps SIGHUP, SIGINT and SIGTERM on UNIX platforms, and uses GtkApplication features to listen to the session manager notifications on logout. When one of these signals is received, we quit gracefully and non-interactively using autosave features added in !109 (merged).
Edited by Gaël Bonithon