Re-enable actions only if edit-save succeeded

Re-enable actions only if edit-save succeeded

Fixes a flaw in `edit_link_save()` in insert.js:

On exit, `edit_link_save()` re-enables all buttons of the action column, regardless of the value of `status` as returned by the ajax call (`action=edit_save`), i.e. also if the `status` is `fail` which means that the edit row remains visible. Because of that, it is then possible to open another edit row for the same keyword/long URL row. It is even possible to repeat this, introducing an arbitrary number of open edit rows with the same content.