Support logging to console only
Support logging to console only

If logger_filename of the actor system configuration is empty, the
logger will only print to the console.

nq-ebaratte/actor-framework,DavadDi/actor-framework,actor-framework/actor-framework,actor-framework/actor-framework,actor-framework/actor-framework,nq-ebaratte/actor-framework,nq-ebaratte/actor-framework,DavadDi/actor-framework,DavadDi/actor-framework,nq-ebaratte/actor-framework,actor-framework/actor-framework,DavadDi/actor-framework