Fixes #145 - always pass a logger name through to log4net's LogManager.GetLogger() call; provide the defaultLoggerName: option on the WriteTo.Log4Net() method to override the default "serilog".
Fixes #164 - convert enum values properly when read from app settings.
Adds serilog:enrich:with-property:PropertyName syntax to the app settings extension.
Adds the Serilog.Extras.Attributed package.