+/**
+ * A data bean that holds
+ * <ul>
+ * <li>feature types and their render order</li>
+ * <li>feature groups and their visibility</li>
+ * <li>colour for each feature type</li>
+ * <li>filters (if any) for each feature type</li>
+ * <li>feature colour transparency</li>
+ * </ul>
+ * Note that feature type visibility settings are not held here.
+ */