stop on TERM signal as well.

which is the proper signal, I think, and it's the one sublime/python
seems to send to subprocesses.

go/qst.go

	go runCmd(file, runner)
	c := make(chan os.Signal, 1)
	signal.Notify(c, os.Interrupt, os.Kill)
	signal.Notify(c, os.Interrupt, os.Kill, syscall.SIGTERM)
	s := <-c
	log.Printf("got signal: %s, exiting...", s)
	runner.Stop()