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/Serializer.java
{
    
    /**
     * Write the chart described by the model to the OutputStream provided.
     * 
     * @param cModel
     *            The model to be serialized os The OutputStream to which the model is to be serialized
     */
    public void write(Chart cModel, OutputStream os) throws IOException;
    /**
     * Write the chart described by the model to the location defined by the URI provided.
     * 
     * @param cModel
     *            The model to be serialized uri The URI to which the model is to be serialized
     */
    public void write(Chart cModel, URI uri) throws IOException;
    /**
     * Write the chart described by the model to a ByteArrayOutputStream.
     * 
     * @param cModel
     *            The model to be serialized bStripHeaders Specifies whether or not the headers are to be removed while