InitLogOptions init log options from config file.

SetLogOptions set the LoggingOptions of NetConf.

DebugLevel logs are typically voluminous, and are usually disabled in production.

DPanicLevel logs are particularly important errors.

ErrorLevel logs are high-priority.

FatalLevel logs a message, then calls os.Exit(1).

InfoLevel is the default logging priority.

PanicLevel logs a message, then panics.

WarnLevel logs are more important than Info, but don't need individual human review.