Old match type "answertypes" now skips RRSIGs.
New "answerrrsigs" type checks counts all types including RRSIGs
and types covered by RRSIGs.

Diffsum configured with priority answertypes > answerrrsigs
produces separate reports for RR types in answer section while ignoring
RRSIGs and another report for differences in RRSIGs for messages where
other answer types match.