Use 8.3 filenames in FixDuplicateItems() too
Use 8.3 filenames in FixDuplicateItems() too

Harden gettext invocation in POCatalog::FixDuplicateItems() against
codepage, whitespace etc. issues using CliSafeFileName() as is done
in other places.

Fixes #763.

alexhenrie/poedit,alexhenrie/poedit,vslavik/poedit,nawawi/poedit,vslavik/poedit,vslavik/poedit,nawawi/poedit,vslavik/poedit,nawawi/poedit,vslavik/poedit,nawawi/poedit,nawawi/poedit,alexhenrie/poedit,alexhenrie/poedit,alexhenrie/poedit