[getdns-api] Cache control

[Joe Hildebrand jhildebr]

In some implementations of the API, the API will have it's own local
cache.  In those cases, as Brad Hill mentioned in appsawg just now, it
would be nice to be able to insert information into the cache, and to
flush the cache.  Are there other operations that would be required?

One use case for this would be getting "trustable" DNS entries from aggsrv
or some other protocol, such that a client could make a connection with
less network round-trips.

-- 
Joe Hildebrand