Feature / Fix: Implement CachingExecutor using cache TTL, deprecate old CachedExecutor,
respect TTL from response records when caching and do not cache truncated responses.
(#129 by @clue)

Feature: Limit cache size to 256 last responses by default.
(#127 by @clue)

Feature: Cooperatively resolve hosts to avoid running same query concurrently.
(#125 by @clue)