Better factorize by reusing code rather than recreating a combo box
which does basically the same thing. I only added a boolean parameter to
retrieve only the sublist of manual language.
It also takes advantage of the self-translated language names from
initialization.
Derive GimpTranslationStore from GimpLanguageStore. It lists the
installed GIMP translations. Also sort the list alphabetically
instead of relying on the XML file being sorted.
