Consider splitting errors into fatal/error/warning/info

[tobez]

Requested by Daniel Stirnimann:

Nonetheless, I think in the long term it could still make sense to provide the granularity of different error levels such as ERROR, WARNING and maybe INFO. For example: you have a buggy signer which leaves some old RRSIGs by accident and your zone is not in an algorithm key rollover state as described above. The operator has enabled the above new policy check because some of his zones do have an algorithm key rollover at one point in time. Without providing different error levels, the operator will not detect this failure in the buggy signer. Maybe you could just log such situations in the "verbose" output so that an operator has the chance to detect them. Current verbose logging would be marked as INFO and more serious none-errors could be marked as WARNING.