More sane triggers in zone...

...so that the .SE-zone (for starters) doesnt generate 50% WARNINGs. Only "expire" is a bit dangerous, kept as WARNING. (For future reference we might want to look at the MNAME-errors also but kept them as WARNING as of now...).
Fixes #139
Merge pull request #141 from einar/master

More sane triggers in zone...
Do not add self-referential fake delegations.
Merge from upstream.