Output a stack trace of unhandled exceptions to a log file

[Killfrra]

Otherwise, it is difficult to debug the server, having access only to the logs. _logger.Error(e) -> _logger.Error(null, e) + Fatal in GameServerConsole.Program.Main just in case everything goes wrong

//     WARNING Note that passing an System.Exception to this method will print the name
//     of the System.Exception but no stack trace. To print a stack trace use the Error(object,Exception)
//     form instead.
void Error(object message);

-- From log4net.ILog