Bug 174872 Clean up chart model
The chart model contains unused attributes and components. Those just make it difficult to understand the model architecture, so they should be removed from the schema, and the EMF classes must re-generated. Examples are: ChartPreferences, Rule. We need to analyze the model to find out all unused ones. Note that this should not break backward compatibility, otherwise just make them deprecated.
chart/org.eclipse.birt.chart.engine/src/org/eclipse/birt/chart/model/component/ChartPreferences.java
* begin-model-doc -->
	 * 
	 * A collection of labels holding preferences for the various labels used in a chart.
	 * 
	 * <!-- end-model-doc -->
	 * 
	 * @return the value of the '<em>Labels</em>' containment reference list.
	 * @see org.eclipse.birt.chart.model.component.ComponentPackage#getChartPreferences_Labels()
	 * @model type="org.eclipse.birt.chart.model.component.Label" containment="true" resolveProxies="false"
	 *        required="true"
	 * @generated
	 */
	EList getLabels( );
	/**
	 * Returns the value of the '<em><b>Blocks</b></em>' containment reference list. The list contents are of type
	 * {@link org.eclipse.birt.chart.model.layout.Block}. <!-- begin-user-doc --> <!-- end-user-doc --> <!--
	 * begin-model-doc -->
	 * 
	 * A collection of blocks holding preferences for the different blocks used in a chart.
	 * 
	 * <!-- end-model-doc -->
	 * 
	 * @return the value of the '<em>Blocks</em>' containment reference list.
	 * @see org.eclipse.birt.chart.model.component.ComponentPackage#getChartPreferences_Blocks()
	 * @model type="org.eclipse.birt.chart.model.layout.Block" containment="true" resolveProxies="false" required="true"
	 * @generated
	 */
	EList getBlocks( );
}