Added a new ''modified:' metadata tag to be able to specify the

publication time and date and the last modified time and date
independently.

This makes it possible to access the last updated date with {{ article.locale_modified }} in templates.
Additionally, an already delivered feed entry can be corrected by changing the modified date and time, as it is used for atom:update
/ rss pubDate field now.

pelican/tests/output/basic/category/bar.html

@@ -30,7 +30,7 @@
                     <h1 class="entry-title"><a href="/oh-yeah.html">Oh yeah !</a></h1>
 <footer class="post-info">
         <abbr class="published" title="2010-10-20T10:14:00">
-                Wed 20 October 2010
+                Published: Wed 20 October 2010
         </abbr>
 
         <address class="vcard author">

pelican/tests/output/basic/category/cat1.html

@@ -30,7 +30,7 @@
                     <h1 class="entry-title"><a href="/a-markdown-powered-article.html">A markdown powered article</a></h1>
 <footer class="post-info">
         <abbr class="published" title="2011-04-20T00:00:00">
-                Wed 20 April 2011
+                Published: Wed 20 April 2011
         </abbr>
 
 <p>In <a href="/category/cat1.html">cat1</a>. </p>
@@ -53,7 +53,7 @@
                 <div class="entry-content">
 <footer class="post-info">
         <abbr class="published" title="2011-02-17T00:00:00">
-                Thu 17 February 2011
+                Published: Thu 17 February 2011
         </abbr>
 
 <p>In <a href="/category/cat1.html">cat1</a>. </p>
@@ -73,7 +73,7 @@
                 <div class="entry-content">
 <footer class="post-info">
         <abbr class="published" title="2011-02-17T00:00:00">
-                Thu 17 February 2011
+                Published: Thu 17 February 2011
         </abbr>
 
 <p>In <a href="/category/cat1.html">cat1</a>. </p>
@@ -93,7 +93,7 @@
                 <div class="entry-content">
 <footer class="post-info">
         <abbr class="published" title="2011-02-17T00:00:00">
-                Thu 17 February 2011
+                Published: Thu 17 February 2011
         </abbr>
 
 <p>In <a href="/category/cat1.html">cat1</a>. </p>

pelican/tests/output/basic/category/misc.html

@@ -30,7 +30,7 @@
                     <h1 class="entry-title"><a href="/filename_metadata-example.html">FILENAME_METADATA example</a></h1>
 <footer class="post-info">
         <abbr class="published" title="2012-11-30T00:00:00">
-                Fri 30 November 2012
+                Published: Fri 30 November 2012
         </abbr>
 
 <p>In <a href="/category/misc.html">misc</a>. </p>
@@ -52,7 +52,7 @@
                 <div class="entry-content">
 <footer class="post-info">
         <abbr class="published" title="2012-02-29T00:00:00">
-                Wed 29 February 2012
+                Published: Wed 29 February 2012
         </abbr>
 
 <p>In <a href="/category/misc.html">misc</a>. </p>
@@ -74,7 +74,7 @@
                 <div class="entry-content">
 <footer class="post-info">
         <abbr class="published" title="2010-10-15T20:30:00">
-                Fri 15 October 2010
+                Published: Fri 15 October 2010
         </abbr>
 
 <p>In <a href="/category/misc.html">misc</a>. </p>
@@ -104,7 +104,7 @@ pelican.conf, it ...</p></div>
                 <div class="entry-content">
 <footer class="post-info">
         <abbr class="published" title="2010-03-14T00:00:00">
-                Sun 14 March 2010
+                Published: Sun 14 March 2010
         </abbr>
 
 <p>In <a href="/category/misc.html">misc</a>. </p>

pelican/tests/output/basic/category/yeah.html

@@ -30,7 +30,7 @@
                     <h1 class="entry-title"><a href="/this-is-a-super-article.html">This is a super article !</a></h1>
 <footer class="post-info">
         <abbr class="published" title="2010-12-02T10:14:00">
-                Thu 02 December 2010
+                Published: Thu 02 December 2010
         </abbr>
 
         <address class="vcard author">