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/data/Rule.java
* @return whether the value of the '<em>Type</em>' attribute is set.
	 * @see #unsetType()
	 * @see #getType()
	 * @see #setType(RuleType)
	 * @generated
	 */
	boolean isSetType( );
	/**
	 * Returns the value of the '<em><b>Value</b></em>' attribute.
	 * <!-- begin-user-doc --> <!-- end-user-doc -->
	 * @return the value of the '<em>Value</em>' attribute.
	 * @see #setValue(String)
	 * @see org.eclipse.birt.chart.model.data.DataPackage#getRule_Value()
	 * @model unique="false" dataType="org.eclipse.emf.ecore.xml.type.String" required="true"
	 *        extendedMetaData="kind='element' name='Value'"
	 * @generated
	 */
	String getValue( );
	/**
	 * Sets the value of the '{@link org.eclipse.birt.chart.model.data.Rule#getValue <em>Value</em>}' attribute. <!--
	 * begin-user-doc --> <!-- end-user-doc -->
	 * 
	 * @param value
	 *            the new value of the '<em>Value</em>' attribute.
	 * @see #getValue()
	 * @generated
	 */
	void setValue( String value );
}