Added preview and sections fields to LMS Topic

- The preview is used to show the details of the topic in the course page
- the sections are used to show the different part of the topic, each could be of a different type

Issue #8

community/www/courses/course.html

@@ -32,10 +32,10 @@
 			{% for topic in course.topics %}
 			<div class="list-group-item">
 				<h5><a href="/courses/topic?course={{course.name}}&topic={{topic.name}}">{{topic.title}}</a></h5>
-				<div>{{topic.description}}</div>
+				<div>{{topic.preview | markdown }}</div>
 			</div>
 			{% endfor %}
 		</div>
 	</div>
 </section>
-{% endblock %}
+{% endblock %}

community/www/courses/course.py

@@ -17,7 +17,7 @@ def get_course(name):
 		filters={
 			'course': name
 		},
-		fields=['name', 'title', 'description'],
+		fields=['name', 'title', 'preview'],
 		order_by='creation'
 	)
 	return course

community/www/courses/topic.html

@@ -19,7 +19,30 @@
 
 		<h1>{{ topic.title }}</h1>
 
-		<div>{{ topic.description }}</div>
+    {% for s in topic.sections %}
+    <div class="section section-{{ s.type }}">
+      {{ render_section(s) }}
+    </div>
+    {% endfor %}
+
 	</div>
 </section>
-{% endblock %}
+{% endblock %}
+
+{% macro render_section(s) %}
+  {% if s.type == "text" %}
+    {{ render_section_text(s) }}
+  {% elif s.type == "code" %}
+    {{ render_section_code(s) }}
+  {% else %}
+    <div>Unknown section type: {{s.type}}</div>
+  {% endif %}
+{% endmacro %}
+
+{% macro render_section_text(s) %}
+  {{ s.contents | markdown  }}
+{% endmacro %}
+
+{% macro render_section_code(s) %}
+<pre>{{s.code}}</pre>
+{% endmacro %}