zone2lmdb and lmdb-backend regression tests
first baby steps to dnssec in lmdb-backend
import dnssec records in lmdb database
get NSECx direct from backend and use it for lmdb-backend
get RRSIGs direct from backend and use it for lmdb-backend
add lmdb-zone to test for generate presigned zones
store lmdb metadata in zone record
fix NSEC in lmdb-backend
unswap ttl and IN in saxfr output