CLJ-1365 - add primitive type hints for new hash functions

Signed-off-by: Stuart Halloway <stu@cognitect.com>
update changelog for 1.6.0-rc1

Signed-off-by: Stuart Halloway <stu@cognitect.com>
[maven-release-plugin] prepare release clojure-1.6.0-RC1
[maven-release-plugin] prepare for next development iteration