Daemon logging redirection

Hi, I've added new flag: --daemon-logging, which causes stdout and stderr file descriptors to be redirected to error-log file. I also set the propagation flags on loggers to False, so the root logger won't double the messages.

This is different from the existing redirection when error-log is not '-', because it affects the low level and, in my case, also the custom C++ module - its messages are now visible in the logs (if the flag is given).

I think it might be useful for other users.