improved task view:

parent task no longer disappears when task is updated

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

frontend/src/routes/task/View.svelte

@@ -143,7 +143,9 @@
         });
         if (resp.ok){
             error = null;
+            let old_task = task;
             task  = await resp.json();
+            if (task.parent_id == old_task.parent_id) task.parent = old_task.parent;
             return true;
         } else {
             error = await resp.text();