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
* 
 * 			This type represents a rule to process a query expression.
 * 			
 * <!-- end-model-doc -->
 *
 * <p>
 * The following features are supported:
 * <ul>
 *   <li>{@link org.eclipse.birt.chart.model.data.Rule#getType <em>Type</em>}</li>
 *   <li>{@link org.eclipse.birt.chart.model.data.Rule#getValue <em>Value</em>}</li>
 * </ul>
 * </p>
 *
 * @see org.eclipse.birt.chart.model.data.DataPackage#getRule()
 * @model extendedMetaData="name='Rule' kind='elementOnly'"
 * @generated
 */
public interface Rule extends EObject
{
	/**
	 * Returns the value of the '<em><b>Type</b></em>' attribute. The default value is <code>"Filter"</code>.
	 * The literals are from the enumeration {@link org.eclipse.birt.chart.model.attribute.RuleType}. <!--
	 * begin-user-doc --> <!-- end-user-doc -->
	 * 
	 * @return the value of the '<em>Type</em>' attribute.
	 * @see org.eclipse.birt.chart.model.attribute.RuleType
	 * @see #isSetType()
	 * @see #unsetType()
	 * @see #setType(RuleType)
	 * @see org.eclipse.birt.chart.model.data.DataPackage#getRule_Type()