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
else
		{
			assert false;
		}
		writer.endElement( );
	}
	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.birt.report.model.elements.ElementVisitor#visitDesignElement(org.eclipse.birt.report.model.core.DesignElement)
	 */
	public void visitDesignElement( DesignElement obj )
	{
		super.visitDesignElement( obj );
		markLineNumber( obj );
		
		attribute( obj, DesignSchemaConstants.NAME_ATTRIB,
				IDesignElementModel.NAME_PROP );
		writer.attribute( DesignSchemaConstants.ID_ATTRIB, new Long( obj
				.getID( ) ).toString( ) );
		attribute( obj, DesignSchemaConstants.EXTENDS_ATTRIB,
				IDesignElementModel.EXTENDS_PROP );
		attribute( obj, DesignSchemaConstants.VIEW_ACTION_ATTRIB,
				IDesignElementModel.VIEW_ACTION_PROP );
		property( obj, IDesignElementModel.COMMENTS_PROP );
		propertyCDATA( obj, IDesignElementModel.CUSTOM_XML_PROP );
		resourceKey( obj, IDesignElementModel.DISPLAY_NAME_ID_PROP,
				IDesignElementModel.DISPLAY_NAME_PROP );
		property( obj, IDesignElementModel.EVENT_HANDLER_CLASS_PROP );
		writeUserPropertyDefns( obj );