Keep PO headers unchanged for existing catalogs

Describe the bug When I load extracted PO catalogs into some sort of editor and do some changes, it does modify headers in its own way. Later when I rerun extract again, headers are again modified, mostly lower casing, but nothing is lost.

This is mostly an issue about file versioning as when headers will be changing between commits, it means a bunch of unrelated changes all the time.

To Reproduce You can use for example known POEdit to see this happening or simply edit PO file manually to change the casing of some header.

Expected behavior Headers should be kept completely unchanged for existing catalogs.

Additional context This is upstream issue https://github.com/smhg/gettext-parser/issues/12 which does not seem to be getting fixed any time soon. So it’s either about forking it or copying out relevant parts.

[tricoder42]

Absolutely! The obsolete flag was just a workaround, because I didn’t know about #~ and simply commenting out msgs didn’t work.

Great job 👏

[tricoder42]

Looks good! Interested in trying it on your own? 😃