Added software page link in header.

Added last build timestamp in footer.

_includes/footer.html

@@ -7,6 +7,9 @@
         <a href="{{ site.website.source }}">Website content</a> is released under the
         <a href="{{ site.website.license.url }}">{{ site.website.license.name }}</a> license
     </div>
+    <div>
+    Website last compiled on {{ site.time | date: '%F %T' }}
+    </div>
     <div>
         &copy; {{ site.time | date: '%Y' }} {{ site.author.name }}
     </div>

_includes/header.html

@@ -1,17 +1,17 @@
 <div class="top">
     <ul>
         <li><a href="#main">Main content</a></li>
-        {% if page.url != '/sitemap/' %}
+        {% if page.permalink != '/sitemap/' %}
             <li><a href="{{ site.baseurl }}/sitemap/">Sitemap</a></li>
         {% endif %}
-	    {% if page.url == '/index.html' or page.url == '/' %}
-    		{% assign link = '/about' %}
-	    	{% assign prompt = 'About' %}
+	    {% if page.permalink == 'index.html' or page.url == '/' %}
+        	<li><a href="{{ site.baseurl }}/about">About</a></li>
     	{% else %}
-	    	{% assign link = '/' %}
-    		{% assign prompt = 'Home' %}
+        	<li><a href="{{ site.baseurl }}/">Home</a></li>
 	    {% endif %}
-    	<li><a href="{{ link | prepend: site.baseurl }}">{{ prompt }}</a></li>
+	    {% if page.permalink != '/software/' %}
+        	<li><a href="{{ site.baseurl }}/software">Software</a></li>
+        {% endif %}
         <li><a href="{{ site.baseurl }}/feed.xml">RSS</a></li>
     </ul>
 </div>