Setting ksk-lifetime option to infinity is not possible

The DNSSEC policy option ksk-lifetime defaults to infinity. I wanted to set this option explicitly to infinity but this seems not possible.

I tried 0, 0d, infinity, -1. I guess if one wants "infinity" he must not set the option at all.

I would suggest to allow setting the default infinity option explicitly. If so, please also make it clear in the documentation what that value would be.