ADD: for language as 'fr-BE', include 'fr' too.

* If a language like 'fr-BE' is chosen, make sure that the base language
  is included as well (ie. 'fr' in this case).
* This allows overriding only some words in languages other than en-US.
* Furthermore, including a language now never fails, no matter if it
  exists or not.


git-svn-id: http://svn.montala.net/svn/resourcespace@5022 c08608d7-6e46-0410-86ca-f2a6f1370df5