Sure, I will submit a patch for the things that are not part of this change. But since this method is new it would be nice to decide on a naming scheme and use it. So we don't need to rename the method later.

I think the shortest naming scheme fits best. A caller of these methods should know he is working with a `...List` object, right?
* `$list->set( $object )`
* `$list->remove( $object )`
* `$list->contains( $object )`
* `$list->getByLanguage( $languageCode )`
* `$list->removeByLanguage( $languageCode )`
* `$list->containsLanguage( $languageCode )`