Bug 123406 Add geLocaltStringProperty in GroupElementHandle and GroupPropertyHandle
Please refer to 123405. GUI need a way to get the local setting of given property because current getStringPropery method will return inherited value if there are no local value.
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/api/GroupElementHandle.java
* 
	 * @return the list that contains the group of design elements.
	 */
	abstract public List getElements( );
	/**
	 * Returns the module.
	 * 
	 * @return the module
	 */
	abstract public Module getModule( );
	/**
	 * Returns the handle of module.
	 * 
	 * @return the handle of module
	 */
	abstract public ModuleHandle getModuleHandle( );
	/**
	 * Indicates that if the given elements are of the same definition. Elements
	 * are considered of same type if their element definitions are identical.
	 * <p>
	 * If elements have different definitions. Even the same element type, the
	 * return value is <code>false</code>. For example, if the list contains
	 * an <code>OdaDataSource</code> and a <code>OdaDataSource</code>, this
	 * method returns <code>false</code>.
	 * 
	 * @return <code>true</code> if the given elements are of the same type;
	 *         return <code>false</code> if elements are of different element
	 *         types, or the given list is empty, or the list contains any
	 *         object that is not an instance of
	 *         <code>DesignElementHandle</code>.