The keyword 'unlimited' can be used instead of PT0S which means the
same but is more comprehensible for users.
Also fix some redundant "none" parameters in the kasp test.
'dnssec-policy' can now also be set on the options and view level and
a zone that does not set 'dnssec-policy' explicitly will inherit it
from the view or options level.
This requires a new keyword to be introduced: 'none'. If set to
'none' the zone will not be DNSSEC maintained, in other words it will
stay unsigned. You can use this to break the inheritance. Of course
you can also break the inheritance by referring to a different
policy.
The keywords 'default' and 'none' are not allowed when configuring
your own dnssec-policy statement.
Add appropriate tests for checking the configuration (checkconf)
and add tests to the kasp system test to verify the inheritance
works.
Edit the kasp system test such that it can deal with unsigned zones
and views (so setting a TSIG on the query).
When doing rollover in a timely manner we need to have access to the
relevant kasp configured durations.
Most of these are simple get functions, but 'dns_kasp_signdelay'
will calculate the maximum time that is needed with this policy to
resign the complete zone (taking into account the refresh interval
and signature validity).
Introduce parent-propagation-delay, parent-registration-delay,
parent-ds-ttl, zone-max-ttl, zone-propagation-delay.
