BibEditMulti: fix for multilanguage interface

* Fixes the errors in the BibEditMulti interface for language
  versions different than English.  (fixes #1331)

* Removes the hardcoded English words in the interface
  and replaces them with the translated ones.

Reported-by: Stefan Hesselbach <s.hesselbach@gsi.de>
Reviewed-by: Javier Martin Montull <javier.martin.montull@cern.ch>