The Atom feed fails validation at http://feedvalidator.org/ because the `<category>` tags are syntactically incorrect ([spec](http://www.atomenabled.org/developers/syndication/atom-format-spec.php#element.category)). With this patch it validates.
-<pre>
-Index: templates/atomitem.tmpl
-===================================================================
---- templates/atomitem.tmpl (revision 2640)
-+++ templates/atomitem.tmpl (working copy)
-@@ -8,7 +8,7 @@
- <link href="<TMPL_VAR PERMALINK>"/>
- <TMPL_IF NAME="CATEGORIES">
- <TMPL_LOOP NAME="CATEGORIES">
-- <category><TMPL_VAR CATEGORY></category>
-+ <category term="<TMPL_VAR CATEGORY>" />
- </TMPL_LOOP>
- </TMPL_IF>
- <updated><TMPL_VAR DATE_3339></updated>
-</pre>
\ No newline at end of file
+ Index: templates/atomitem.tmpl
+ ===================================================================
+ --- templates/atomitem.tmpl (revision 2640)
+ +++ templates/atomitem.tmpl (working copy)
+ @@ -8,7 +8,7 @@
+ <link href="<TMPL_VAR PERMALINK>"/>
+ <TMPL_IF NAME="CATEGORIES">
+ <TMPL_LOOP NAME="CATEGORIES">
+ - <category><TMPL_VAR CATEGORY></category>
+ + <category term="<TMPL_VAR CATEGORY>" />
+ </TMPL_LOOP>
+ </TMPL_IF>
+ <updated><TMPL_VAR DATE_3339></updated>
\ No newline at end of file