Bug 174272 FileStoreEditorInput needs to be restorable
3.3 M5 The FileStoreEditorInput needs to restorable on startup. Therefore it needs to return an IPersistableElement and there needs to be an element factory.
bundles/org.eclipse.ui.ide/src/org/eclipse/ui/ide/IDE.java
* <p>
	 * If the page already has an editor open on the target object then that
	 * editor is brought to front; otherwise, a new editor is opened.
	 * </p>
	 * 
	 * @param page
	 *            the page in which the editor will be opened
	 * @param uri
	 *            the URI of the file store representing the file to open
	 * @param editorId
	 *            the id of the editor extension to use
	 * @param activate
	 *            if <code>true</code> the editor will be activated opened
	 * @return an open editor or <code>null</code> if an external editor was
	 * @exception PartInitException
	 *                if the editor could not be initialized
	 * 
	 * @see org.eclipse.ui.IWorkbenchPage#openEditor(IEditorInput, String)
	 * @see EFS#getStore(URI)
	 * 
	 * @since 3.3
	 */
	public static IEditorPart openEditor(IWorkbenchPage page, URI uri,
			String editorId, boolean activate) throws PartInitException {
		
		if (page == null) {
			throw new IllegalArgumentException();
		}
		IFileStore fileStore;
		try {