feat: Add additional scan time options

- Add option to include file existence check at end of scan, speeds up
  end of scan operation time considerably, however if user has removed
  or moved files since starting a scan there could be later errors when
  interacting with results.  Defaults to existing behavior of including
  the check, until it can be verified later dialogs and actions handle
  non-existent items better.
- Add option to ignore differences in mtime when checking hash cache.
  Option is present in advanced tab of preferences.  Closes #1022.
- Regenerate pot files for translations

qt/app.py

@@ -193,6 +193,8 @@ class DupeGuru(QObject):
         self.model.options["scanned_tags"] = scanned_tags
         self.model.options["match_scaled"] = self.prefs.match_scaled
         self.model.options["picture_cache_type"] = self.prefs.picture_cache_type
+        self.model.options["include_exists_check"] = self.prefs.include_exists_check
+        self.model.options["rehash_ignore_mtime"] = self.prefs.rehash_ignore_mtime
 
         if self.details_dialog:
             self.details_dialog.update_options()