code: public void add_logging_target (Logger logger, String ttype, String tname) throws DevFailed
  	{
      add_logging_target(logger, ttype + LOGGING_SEPARATOR + tname);
  	}
docs: Adds a logging target to the specified logger (i.e. device).
  
  @param 	logger A lo4j logger to which the target will be added
  @param 	ttype The target type
  @param 	tname The target name