prep for 6.0.0

Author: mceachen

CHANGELOG.md

@@ -1,6 +1,14 @@
 # Changelog
 
+### 6.0.0
+
+* [Andrew Kumanyaev](https://github.com/zzet) *dramatically* improved mutation performance on large trees. 
+  Thanks for the PR!
+* [Martin Schmidt](https://github.com/martin-schmidt) discovered and fixed build problems due to new versions 
+  of mysql2 and ammeter which broke Travis builds. Thanks for the PR!
+
 ### 6.0.0.alpha,beta,gamma
+
 * Dropped support for versions of Rails 3.2 and 4.0 (which are no longer supported).
 * Dropped support for Ruby 1.9 and JRuby 1.9 (which are no longer supported).
 * Added support for `.hash_tree` from `.parent` and `.children`. 

lib/closure_tree/version.rb

@@ -1,3 +1,3 @@
 module ClosureTree
-  VERSION = Gem::Version.new('6.0.0.gamma')
+  VERSION = Gem::Version.new('6.0.0')
 end