- add conversion modules for other Unicode encodings than UTF-8 
  (UTF-16, UCS-*)

- Better support for Windows, the locale detection stuff does not
  really work there.  Any help would be appreciated.

- Check whether other locale categories than LC_MESSAGES work.

- Avoid call to __load_domain in Locale::gettext_pp, use a cache table
  first

- The pure Perl version of gettext will always look for message catalogs
  in /usr/share/locale/{LANGUAGE}/LC_MESSAGES after the directory
  specified by bindtextdomain().  This can lead to undesired results.
  But I think the C version from libintl does the same, correct?

- Allow to dynamically expand the list of supported conversions

- Allow to dynamically restrict the list of suppported conversions