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/impl/LayoutPackageImpl.java
* Note: the correct way to create the package is via the static factory
	 * method {@link #init init()}, which also performs initialization of the
	 * package, or returns the registered package, if one already exists. <!--
	 * begin-user-doc --> <!-- end-user-doc -->
	 * 
	 * @see org.eclipse.emf.ecore.EPackage.Registry
	 * @see org.eclipse.birt.chart.model.layout.LayoutPackage#eNS_URI
	 * @see #init()
	 * @generated
	 */
	private LayoutPackageImpl( )
	{
		super( eNS_URI, LayoutFactory.eINSTANCE );
	}
	/**
	 * <!-- begin-user-doc --> <!-- end-user-doc -->
	 * @generated
	 */
	private static boolean isInited = false;
	/**
	 * Creates, registers, and initializes the <b>Package</b> for this
	 * model, and for any others upon which it depends.  Simple
	 * dependencies are satisfied by calling this method on all
	 * dependent packages before doing anything else.  This method drives
	 * initialization for interdependent packages directly, in parallel
	 * with this package, itself.
	 * <p>Of this package and its interdependencies, all packages which
	 * have not yet been registered by their URI values are first created
	 * and registered.  The packages are then initialized in two steps:
	 * meta-model objects for all of the packages are created before any