Fixed: one error (Abiword 2.9 development)

I just ran a msgfmt check on the .po file with the Dutch translation
of Abiword 2.9 (development) that I just submitted, and it showed one
error.

I've repaired it in the attached file. Please ignore the previous
version and only use this one.

Next time I'll try to remember to use msgfmt earlier on.
How about using Transifex or Pootle, by the way? That would be very
helpful for us translators.

Regards, Pjotr.