Remove extensions from _includes to simplify naming

_pages/year-archive.html

@@ -5,7 +5,7 @@ title: "Posts by Year"
 author_profile: false
 ---
 
-{% include absolute-url.liquid %}
+{% include base_path %}
 {% capture written_year %}'None'{% endcapture %}
 {% for post in site.posts %}
   {% capture year %}{{ post.date | date: '%Y' }}{% endcapture %}
@@ -13,5 +13,5 @@ author_profile: false
     <h3>{{ year }}</h3>
     {% capture written_year %}{{ year }}{% endcapture %}
   {% endif %}
-  {% include archive-list-single.html %}
+  {% include archive-list-single %}
 {% endfor %}