[i18n] Slovak translation update

[Ivan Noris]

I've updated the translations once again. Some cleanups are done and I'm
starting to translate the "translation.php" messages itself.

Please commit Horde, IMP and Turba translations (HEAD) from:
www.vazka.sk/~vix/horde-cvs/

Thanks,
VIX
-- 
  Ing. Ivan Noris
  System engineer, Business Global Systems, a.s.
  info & public key: http://www.bgs.sk/people/noris
  __________________________________________________________________
  "Semper cautus - semper paratus - semper idem Vix."