Implement support for auto-restarting unique-applications after a crash. Inspired by the non-working handler in kded and the working handler in plasma, but fixing segv handling in the restarted-application (thanks to mornfall and SadEagle for their input).
Also fixed handling of KDE_DEBUG=1 and --nocrashhandler: they both mean "no drkonqi please", even if we set up a crashhandler to handle "emergency save" and "autorestart" functionality.
I'll port plasmaapp.cpp and krunner to KCrash::AutoRestart on Monday.