delv +ns (name server mode) to replace "dig +trace"

Something I've had on my things-to-do list for a few years now: add an option to delv that makes it instantiate a full internal recursive resolver and use that to resolve the specified query. The results would be similar to dig +trace - which has always been rather buggy - but since it would be using the same code as named, it would exactly reproduce the behavior of a name server with a cold cache performing a recursive lookup. dig +trace can be deprecated once this feature is in place.