WPXRSS importer added.

lang/UTF-8/serendipity_lang_ru.inc.php

@@ -899,3 +899,4 @@ $i18n_filename_to   = array('_', 'a', 'A', 'b', 'B', 'v', 'V', 'g', 'G', 'd', 'D
 @define('PINGBACK_FAILED', 'Pingback failed: %s');
 @define('PINGBACK_NOT_FOUND', 'No pingback-URI found.');
 @define('CATEGORY_PLUGIN_HIDEZEROCOUNT', 'Hide archives link when no entries were made in that timespan (requires counting entries)');
+@define('RSS_IMPORT_WPXRSS', 'WordPress eXtended RSS import, requires PHP5 and might take up much memory');