* Extend language::getLanguageName to return localized language names if available

* Extend language::getLanguageName to return localized language names if available
* Therefore added a hook to catch them from an extension (successfully tested with the cldr extension (see next commit))
* Add a title tag to the interlanguage box entries. Only added when the title differ from the shwon text.
No change of behaviour until an extension is enabled.