implemented option to list tasks without rendering markdown

Signed-off-by: Stephan Richter <s.richter@srsoftware.de>

frontend/src/routes/project/Kanban.svelte

@@ -178,6 +178,7 @@
         const url            = api('task/list');
         selector.show_closed = true;
         selector.no_index    = true;
+        selector.rendered    = false;
         var resp = await post(url,selector);
         if (resp.ok){
             var json = await resp.json();