PoChecker:
- Add capability to scan a folder for po-files.
- Add files to a listbox.
- Add filter for language to listbox with translated po-files.
- Save and restore contents of the file lists.
- Regenerate language files.


git-svn-id: http://svn.freepascal.org/svn/lazarus/trunk@46394 4005530d-fff6-0310-9dd1-cebe43e6787f