message: Better file opening prompts: don't say "catalog"
  Change prompts for opening translation files and POTs to talk about
  translation files, not about catalogs, which is gettext-ism.
diff: @@ -968,7 +968,7 @@ void PoeditApp::OnNewFromPOT(wxCommandEvent& event)
  win.NotifyIsStarting();
  wxString path = wxConfig::Get()->Read("last_file_path", wxEmptyString);
  wxString pot_file =
  - wxFileSelector(MACOS_OR_OTHER("", _("Open catalog template")),
  + wxFileSelector(MACOS_OR_OTHER("", _("Select translation template")),
  path, wxEmptyString, wxEmptyString,
  Catalog::GetTypesFileMask({Catalog::Type::POT, Catalog::Type::PO}),
  wxFD_OPEN | wxFD_FILE_MUST_EXIST, win.GetParentWindowIfAny());
  @@ -1007,7 +1007,7 @@ void PoeditApp::OnOpen(wxCommandEvent& event)
  wxString path = wxConfig::Get()->Read("last_file_path", wxEmptyString);
  wxFileDialog dlg(win.GetParentWindowIfAny(),
  - MACOS_OR_OTHER("", _("Open catalog")),
  + MACOS_OR_OTHER("", _("Select translation file")),
  path,
  wxEmptyString,
  Catalog::GetAllTypesFileMask(),
  