Fix #168; when nailing a spammer, clear their profile text fields. Guard against topics and forums that don't exist when deleting posts in the signal handler. Make the forum stats template tag only display the latest active users.

<div class="side-block">
<div class="side-block-title">
{% block block_title %}{% endblock %}
</div>
<div class="side-block-content">
{% block block_content %}{% endblock %}
</div>
</div>