Bug 213126 Add support for DataEngine-leve dataset cache
In many cases the DataEngine-leve dataset cache is useful which ensure that a dataset is executed one time during rendering one report. To support this feature a new dataset property should be added. The Birt customer can choose whether this dataset need to be cached or not by setting the property in deisgn time.
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/writer/ModuleWriter.java
writer.startElement( DesignSchemaConstants.ODA_LEVEL_TAG );
		super.visitOdaLevel( obj );
		writer.endElement( );
	}
	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.birt.report.model.elements.ElementVisitor#visitOdaMeasure(org.eclipse.birt.report.model.elements.olap.OdaMeasure)
	 */
	public void visitOdaMeasure( OdaMeasure obj )
	{
		writer.startElement( DesignSchemaConstants.ODA_MEASURE_TAG );
		super.visitOdaMeasure( obj );
		writer.endElement( );
	}
	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.birt.report.model.elements.ElementVisitor#visitOdaMeasureGroup(org.eclipse.birt.report.model.elements.olap.OdaMeasureGroup)
	 */
	public void visitOdaMeasureGroup( OdaMeasureGroup obj )
	{
		writer.startElement( DesignSchemaConstants.ODA_MEASURE_GROUP_TAG );
		super.visitOdaMeasureGroup( obj );
		writer.endElement( );
	}
	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.birt.report.model.elements.ElementVisitor#visitFilterConditionElement(org.eclipse.birt.report.model.elements.FilterConditionElement)