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/attribute/RuleType.java
* <!-- end-user-doc -->
	 * @see #FILTER_LITERAL
	 * @model name="Filter"
	 * @generated
	 * @ordered
	 */
	public static final int FILTER = 0;
	/**
	 * The '<em><b>Suppress</b></em>' literal value.
	 * <!-- begin-user-doc
	 * --> <!-- end-user-doc -->
	 * @see #SUPPRESS_LITERAL
	 * @model name="Suppress"
	 * @generated
	 * @ordered
	 */
	public static final int SUPPRESS = 1;
	/**
	 * The '<em><b>Link</b></em>' literal value.
	 * <!-- begin-user-doc -->
	 * <!-- end-user-doc -->
	 * @see #LINK_LITERAL
	 * @model name="Link"
	 * @generated
	 * @ordered
	 */
	public static final int LINK = 2;
	/**
	 * The '<em><b>Filter</b></em>' literal object.
	 * <!-- begin-user-doc -->