add gallery shortcode

templates/shortcodes/gallery.html

@@ -0,0 +1,16 @@
+{# {{ gallery(images=[], cols=2, caption="") }} #}
+
+{% if not cols %}
+    {% set cols = 2 %}
+{% endif %}
+
+<figure>
+    <div class="gallery{{cols}}">
+        {% for image in images %}
+            {% set url = image | first %}
+            {% set alt = image | last %}
+            <img src="{{ get_url(path=url) }}" alt="{{ alt }}" title="{{ alt }}">
+        {% endfor %}
+    </div>
+    {% if caption %}<figcaption>{{ caption }}</figcaption>{% endif %}
+</figure>