[horde] Dutch language pack breaks latest stable horde

[Jochem Meyers]

When selecting the dutch (Nederlands) language from the login screen, after
logging in, we get these errors in our horde 3.1.1 installation:
In the main frame, on the right:
Fatal error: Call to undefined function: hasrecurtype() in
/srv/www/htdocs/horde/kronolith/lib/Kronolith.php on line 381

In the sidebar, on the left.
Fatal error: Call to undefined function: getrecurtype() in
/srv/www/htdocs/horde/kronolith/lib/Driver/kolab.php

When picking english as a language, or a number of other non-english
languages such as persian, it works fine, with no errors.