[GRASS-translations] Preparing the upcoming GRASS 6.4.2 release: po files updated

[Markus Neteler]

Dear translators,

after several months and a "hot" summer of improvements for GRASS
I have updated all message files again to reflect latest code changes.
We try to stabilized the messages in order to minimize the translation
efforts.

We hope to release GRASS 6.4.2 in October, hence I would like to
invite you to continue with your translations efforts.

As usual: please submit often (to me) and I'll merge in the updates.

Thanks!
Markus