添加站内消息，修复讨论节点丢失的问题

templates/training_detail.html

@@ -114,7 +114,7 @@
                 {% endif %}
                   <td class="col--name col--problem-name">
                   {% if handler.hasPerm(perm.PERM_LOGGEDIN) %}
-                    <form class="form--inline" action="{{ reverse_url('problem_main') }}" method="post">
+                    <form class="form--inline" action="/p" method="post">
                       <input type="hidden" name="pid" value="{{ pdoc['_id'] }}">
                       <input type="hidden" name="operation" value="{% if not psdoc['star'] %}star{% else %}unstar{% endif %}">
                       <input type="hidden" name="csrfToken" value="{{ handler.csrfToken }}">