Send encoding information in rss header

templates/rss/header.tmpl

@@ -1,6 +1,7
-Content-type: text/xml
+Content-type: text/xml; charset={encoding}
 
+<?xml version="1.0" encoding="{encoding}"?>
 <rss version="2.0">
   <channel>
     <link>{urlbase}{url}</link>
     <language>en-us</language>