Yet more gnome-games string changes

[callum physics otago ac nz]

When updating the menu code for blackjack it appears that the N_() and _()
stuff got dropped. This has been re-instated and so strings will suddenly
appear for translation that had dropped out a month or so ago. You should
be able to pull most of the translations out of the 2.8 branch since I
don't think many (if any) strings changed.

Sorry for the inconvenience.

 - Callum