fix a bug where ev_sender wasn't properly set, and convert sender, arg, action, etc. to ev_sender, ev_arg, ev_action, etc.

do range checks before verify, since it's faster.

for positive validations, but does not yet handle things like shutdown
correctly

fixes.

or vice versa, the resolver could catch an assertion or lose signature data,
respectively.

                        dns/rbt.h; it was needed only by compress.c and zt.c.

                        and dns_rbt_deletenode was added.

deletion no long requires a valid chain.  chain gook removed from all
of the deletion functions.

Minor unrelated doc & code convention cleanups.

Prototyped and documented dns_rbt_deletenode.

negatively cached.