Update *.po with git.pot?

[Ralf Thielow <ralf.thielow@gmail.com>]

When a translation round starts for a Git release, the
git.pot file will be updated and translators msgmerge
their .po-files accordingly before translating. This results
in a huge change to the .po-file as line numbers and
stuff gets updated.

Since translations are made in one commit, this commit
is messed up with the msgmerge update so when you
look at the commit later, you'll have a hard time to find
out what the actual changes in translations were.

We could improve this by making git.pot-updates update
the *.po files as well, so further updates from translators
will only contain actual translations. I think this is what the
gitk project does. It will make the history of *.po-files much
more readable.

Ralf