bugfix: wrong page id saved

The current page has to be returned, not the last one. This would lead
to permanently wrong page ids, so that later no page is accessible.

src/data.c

@@ -137,7 +137,9 @@ SH_Data_register_page (struct SH_Data * data, const char * name,
 		return PAGE_ERR;
 	}
 
-	data->pages[data->page_n].id = NEXT_PAGE(data->last_page);
+	NEXT_PAGE(data->last_page);
+
+	data->pages[data->page_n].id = data->last_page;
 	data->pages[data->page_n].name = strdup (name);
 
 	if (errno == ENOMEM)