Add subtitles to articles

Fix #152

templates/macros.html.tera

@@ -2,7 +2,13 @@
     <div class="card">
         <h3><a href="{{ article.url }}">{{ article.post.title }}</a></h3>
         <main
-            <p>{{ article.post.content | safe | striptags | truncate(length=200) }}</p>
+            <p>
+                {% if article.post.subtitle | length > 0 %}
+                    {{ article.post.subtitle }}
+                {% else %}
+                    {{ article.post.content | safe | striptags | truncate(length=200) }}
+                {% endif %}
+            </p>
         </main>
         <p class="author">
         	{{ "By {{ link_1 }}{{ link_2 }}{{ link_3 }}{{ name | escape }}{{ link_4 }}" | _(

templates/posts/details.html.tera

@@ -11,6 +11,7 @@
 
 {% block content %}
     <h1 class="article">{{ article.post.title }}</h1>
+    <h2 class="article">{{ article.post.subtitle }}</h2>
     <p class="article-info">
         <span class="author">{{ "Written by {{ link_1 }}{{ url }}{{ link_2 }}{{ name | escape }}{{ link_3 }}" | _(
             link_1='<a href="/@/',

templates/posts/new.html.tera

@@ -9,6 +9,7 @@
 <h1>{{ "Create a post" | _ }}</h1>
 <form class="new-post" method="post">
     {{ macros::input(name="title", label="Title", errors=errors, form=form, props="required") }}
+    {{ macros::input(name="subtitle", label="Subtitle", errors=errors, form=form, optional=true) }}
 
     {% if errors is defined and errors.content %}
         {% for err in errors.content %}