Fix problem when deleting multiple topics from a forum in bulk. We getting a list of topics from the database, then deleting each topic. But after you delete a topic, the forum.last_post on the remaining non-deleted topics can be stale. This was causing a weird DoesNotExist. Now just get the topics one at a time from the database.

{% load core_tags %}
<form action="." method="post">{% csrf_token %}
<fieldset>
<legend>{{ legend_text }}</legend>
{{ form.as_p }}
{% comment_dialogs %}
<input type="submit" value="{{ submit_value }}" {% if is_ajax %}id="forums-reply-post"{% endif %} />
</fieldset>
</form>