Improve sorting toggle behavior

Last sorted column now takes precedence over any previously sorted
columns. This makes for a more intuitive user experience.

ui/virtual-parameters-page.ts

@@ -173,14 +173,16 @@ export const component: ClosureComponent = (): Component => {
         sortAttributes[i] = sort[attributes[i].id] || 0;
 
       function onSortChange(sortAttrs): void {
-        const _sort = Object.assign({}, sort);
+        let _sort = Object.assign({}, sort);
         for (const [index, direction] of Object.entries(sortAttrs)) {
           // Changing the priority of columns
           delete _sort[attributes[index].id];
-          _sort[attributes[index].id] = direction;
+          if (direction)
+            _sort = Object.assign({ [attributes[index].id]: direction }, _sort);
         }
 
-        const ops = { sort: JSON.stringify(_sort) };
+        const ops = {};
+        if (Object.keys(_sort).length) ops["sort"] = JSON.stringify(_sort);
         if (vnode.attrs["filter"]) ops["filter"] = vnode.attrs["filter"];
         m.route.set("/admin/virtualParameters", ops);
       }