Robot OS system-wide logging mechanism

 This package is part of Robot OS (ROS). rosout is the name of the
 console log reporting mechanism in ROS. It can be thought of as
 comprising several components:
  * The `rosout` node for subscribing, logging, and republishing the
    messages.
  * The /rosout topic
  * The /rosout_agg topic for subscribing to an aggregated feed