#014076: Language attribute for feed items

It is currently not possible to define a language for a feed item (at least for RSS2 it is not rendered). It should be possible to define the language of a feed item, if it differs from the main language of the feed. This is important for multilingual feeds.

The "xml:lang" attribute can be used, if a feed definition does not allow the item language to be defined in a different way.

I'd expect the behavior to be like this:

$feed = new ezcFeed();

$feed->title = 'eZ news feed';
$feed->language = "en";
// ...

$item = $feed->add( 'item' ); 

$item->title = 'eZ Components 2007.1 released';
$item->language = "de";
// ...

echo $feed->generate( 'rss2' );

will create a feed like this:

<?xml version="1.0" encoding="utf-8"?>
<rss version="2.0">
  <channel>
    <title>eZ news feed</title>
    <language>en</language>
    <!-- ... -->
    <item xml:lang="de">
      <title>eZ Components 2007.1 released</title>
      <!-- ... -->
    </item>
  </channel>
</rss>

Operating System:
PHP Version: (please be specific, like '4.4.3' or '5.1.5')
Database and version:
Browser (and version):