LOGIC-119: quick fix to ensure disunify on maps can deal with non-map other.
first pass at new table cache type. nondeterminism and general bad
behavior in tabling results from the `(first ansv*)` line in the
implementation of `reuse` - there's no guarantee what that will return
for sets. Ooops.
LOGIC-112: Incorrect results with tabled resolution

The bug was introduced when we switched the answer cache to sets. In
`reuse` we were calling `first` on the set which of course won't
work.

We not have an `AnswerCache` type. This holds both the list of answers
for determining the fixpoint as well as the answers as a set for
quickly determining whether we've already cached an answer.

The additionally memory overhead does make it desirable to have more
sharing of tabled information between answer caches.
Merge branch 'master' of github.com:clojure/core.logic
optimization
include 112 test case
bump version
[maven-release-plugin] prepare release core.logic-0.8.0-rc3
[maven-release-plugin] prepare for next development iteration
0.8.0
[maven-release-plugin] prepare release core.logic-0.8.0
[maven-release-plugin] prepare for next development iteration
walk-term for ISeqs should not be lazy, refs #121

Attach metadata only to terms that support it, refs #120

lvars-store should be a map and not a set, refs #122

Tests for LOGIC-120, LOGIC-121 and LOGIC-122
Merge branch 'master' of github.com:clojure/core.logic
LOGIC-116: In `migrate` the root may not have an entry in `km`, we
need to return the empty set in that case, otherwise will we'll call
into on nil which defaults to a seq causing the set only operations
like `disj` to fail.
LOGIC-71: fixed unifier reify vars issue some time ago. Documenting
the fix with a test.
LOGIC-36: another old unifier issue since resolved in 0.8.0. Adding a
test to document.
LOGIC-83: fix typo in test
LOGIC-108: recursive featurec. Add protocol IFeature. Implementers
should return something which can optional unify in the manner of
partial-map. Extend IPersistentHashMap to IFeature. Add test cases
demonstrating recursive behavior.
0.8.1