Bug 165188 logging per report
Setting up a dedicated (birt) report server, which serves all our web apps, leads to a logging desaster. Birtegine logs all messages to one file. There's no info which rptdesign caused the logmessage or who (e.g. user) caused the logmessage. Retrieving who/which rpt caused some logmessage is not possible! There are two possible solutions: (a) prefixing each logmessage with a userdefineable message (task.setLogprefix("myprefix")) (b) set an outputstream for each task (task.setLoggingOutputStream(outputstream)) to split the huge logfile to many small pieces.
engine/org.eclipse.birt.report.engine/src/org/eclipse/birt/report/engine/api/impl/EngineTask.java
* task identifier. Could be used for logging
	 */
	protected int taskID;
	protected IReportRunnable runnable;
	/**
	 * options used to render the report design.
	 */
	protected IRenderOption renderOptions;
	/**
	 * emitter id
	 */
	protected String emitterID;
	/**
	 * does the parameter has been changed by the user.
	 */
	protected boolean parameterChanged = true;
	/**
	 * The parameter values that the caller has set explicitly
	 */
	protected HashMap inputValues = new HashMap( );
	/**
	 * The parameter values that will be used to run the report. It is a merged
	 * map between the input value and the default values.
	 */
	protected HashMap runValues = new HashMap( );
	/**
	 * Engine task type. for usage in BIRT scripting.
	 */
	protected int taskType = IEngineTask.TASK_UNKNOWN;
	/**