[l10n] Update German translation
[l10n] Update of Portugese translation

Thanks to José Carlos.
Minor style fixes.
updated copyright year in about dialog to 2013
Minor style fix.
Fix crash (double deallocation).

Indeed, description is set to point to caption. So both pointer are
pointing to the same data. We do not want to deallocate both.
Make rate applying more consistent and give more information

  * If only one image is seen, any rating done by using the lower panel or
  keyboard should apply to it, whatsoever the current selection is.
  * If the key accels are used to rate any image that is selected,
  the rate should be applied to all the selection.

In general, all the ratings done should show a toast message saying that the
rating has been applied, and the affected images.
Remove spurious dt_control_queue_redraw_center() call
Make colorlabels have the same behaviour than ratings