The *.po files can and should be kept in sync with the source code by running
update.sh regularly (existing translations won't be removed).
+NOTE: Remember to remove X-Virgin-Header line if you want to preserve your header.
+
Qt itself does not use the *.po files, but a compact binary format (*.qm).
These files will automatically be generated at build time. By default, all
languages will be built. To select languages, add -DLINGUAS="<languages>"