Fix errors in po files. Trying to get translation files in shape for translationproject.org. Not sure it wil happen but this checkin fixes errors in .po files found by msgfmt -cv. Recreated template and merged into .po files. Also adds potest to makefile targets and improves diff target. Fixes: Project-Id-Version changed to 2.3.0. I can't find doc on what this is supposed to be. I assume it is to match the .po file to the release since there are other fields for recording the last update to the translations. Language header, is often blank. Added Language-Team value where missing. Plural-Forms header for a couple of languages per: https://www.gnu.org/software/gettext/manual/html_node/Plural-forms.html Japanese still has an issue. There are plural forms defined in the file, but according to the above, there should only be one form. I don't know Japanese, so am not qualified to remove the plural forms or change the Plural-Forms header to the expected: nplurals=1; plural=0; So I have left it with: nplurals=2; plural=0;\n" Which will always choose the first plural form (index 0). Added Last-Translator, Language and Content-Transfer-Encoding for en.po.