[master] Rename one interface: from lookupClosestRRset() to lookupDeepestNS(), and remove one parameter of it.

compression mode.

they appeared to still have been too low for some systems

the previous code used time_t, as a result of copying the pre #61 version,
which may not always be 64-bit.

(going to directly push it.)

skipping review.

I'm not sure why this has been disabled until now, but it seems to me
just about test data preparation.  so I fixed it that way.
should be quite trivial, and test actually passed.  directly pushing,
skipping review.

but it was missing so far and should be provided.

Also added more detailed tests.

There was mix of descriptions with and without trailing periods.
For short phrases maybe a period is not needed, but some
complete sentences were missing.
Since it was a mix I just added the periods to all.
Now there are descriptions within spec files that are not consistent too,
but I don't look at that now.

This was not reviewed.