Add an RSS feed for the blog

creates the feed/blog.xml file
adds the link to the feed as an alternate link in the header for the blog layout
which will let rss readers autodetect the feed from the blog url

Author: jeantil

_layouts/blog.html

@@ -4,6 +4,7 @@
 ---
 
 {% include headertop.html %}
+<link href="/feed/blog.xml" rel="alternate" type="application/rss+xml" title="Scala-lang's blog" />
 {% include headerbottom.html %}
 
 <div class="darkstrip"></div>

feed/blog.xml

@@ -0,0 +1,25 @@
+---
+layout: nil
+---
+<?xml version="1.0" encoding="utf-8"?>
+<feed xmlns="http://www.w3.org/2005/Atom">
+  <title type="text" xml:lang="en">{{ site.root_desc }}</title>
+  <link type="application/atom+xml" href="http://www.scala-lang.org/feed/blog.xml" rel="self"/>
+  <link type="text" href="http://www.scala-lang.org/" rel="alternate"/>
+  <updated>{{ site.time | date_to_xmlschema }}</updated>
+  <id>http://www.scala-lang.org/</id>
+  <author>
+    <name>École Polytechnique Fédérale de Lausanne</name>
+  </author>
+  <rights>Copyright (c) 2002-{{ site.time | date:"%Y" }} École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland</rights>
+
+  {% for post in site.categories.blog limit:20 %}
+  <entry>
+    <title>{{ post.title }}</title>
+    <link href="http://www.scala-lang.org{{ post.url }}"/>
+    <updated>{{ post.date | date_to_xmlschema }}</updated>
+    <id>http://www.scala-lang.org{{ post.id }}</id>
+    <content type="html">{{ post.content | xml_escape }}</content>
+  </entry>
+  {% endfor %}
+</feed>