Bug 207268 Add visibility option for plot within axes
For chart with axes, we should make plot within axes invisible. Meantime, other plots, such as axes, legend and title, should be visible. This enhancement doesn't include UI change, and it is required for cross tab integration.
chart/org.eclipse.birt.chart.engine/src/org/eclipse/birt/chart/model/layout/LayoutPackage.java
* The number of structural features of the '<em>Label Block</em>' class.
	 * <!-- begin-user-doc --> <!-- end-user-doc -->
	 * @generated
	 * @ordered
	 */
	int LABEL_BLOCK_FEATURE_COUNT = BLOCK_FEATURE_COUNT + 1;
	/**
	 * The meta object id for the '{@link org.eclipse.birt.chart.model.layout.impl.LegendImpl <em>Legend</em>}' class.
	 * <!-- begin-user-doc --> <!-- end-user-doc -->
	 * @see org.eclipse.birt.chart.model.layout.impl.LegendImpl
	 * @see org.eclipse.birt.chart.model.layout.impl.LayoutPackageImpl#getLegend()
	 * @generated
	 */
	int LEGEND = 3;
	/**
	 * The feature id for the '<em><b>Children</b></em>' containment reference list.
	 * <!-- begin-user-doc --> <!-- end-user-doc -->
	 * @generated
	 * @ordered
	 */
	int LEGEND__CHILDREN = BLOCK__CHILDREN;
	/**
	 * The feature id for the '<em><b>Bounds</b></em>' containment reference.
	 * <!-- begin-user-doc --> <!-- end-user-doc -->
	 * @generated
	 * @ordered
	 */
	int LEGEND__BOUNDS = BLOCK__BOUNDS;
	/**
	 * The feature id for the '<em><b>Anchor</b></em>' attribute. <!--