Clojurians Log v2

any objections to this before I start putting together a patch? https://clojure.atlassian.net/browse/CLJS-3200

basically will add this to cljs.core and make the desctructure macro use it instead of emitting the implements? check

(defn destructure-map [arg]
  (if (implemements? ISeq arg) (apply hash-map arg) arg))