The `zone_expire()` will return `false` if we don't know when the zone
expires. This is tricky when used as `!zone_expire()`. We have to check
explicitly if the SOA expire value is know.

This Is Pragmaaa!

contexts.

- Also removed knot_ from changesets

issue #1

issue #1

- Zones are now automatically (re)signed when server starts/reloads
- Signature validity check now calculates the signature as well - this is used to detect changes to RRs themselves
- 'knotc signzone' issues a force signing of zone - all RRSIGs are dropped and recreated
- Some leaks and bugs still present, but the code is commitable now

Refs #4

- the result is written as a set of operations into a changeset
  instead of creating a whole new zone tree
- works only for NSEC3 at the moment

- slightly modifies interface for zone contents diffing
  (shorter name, add changesets flags parameter)
- new function works the same with other arguments

Refs #1752 @0.15h

- Needs testing
- Memory leaks have to be fixed

Refs #1752 @5h

Refs #1752 @1.h

- Debugging didn't work, printfs will have to be replaced.
- Several fixes
- Some debug code still present that has to be removed.
- no handling for RRSIGs
- not sure how will this perform in case of empty NSEC3 trees.

Refs #1752 @5h

- Fixed API
- Adding new node from second zone

refs #1752

- Fixed all syntax errors
- Some functions still not writen

- Changed API
- Basic handling of node-diff.

- mostly stubs, uncompilable

 KNOT -> KNOTD
 DNSLIB -> KNOT

refs #1087 @20m

Commit refs #799.