Merge branch 'hotfix/deprecate-callback-handler' into develop

Forward port #35

Author: mwillbanks

CHANGELOG.md

@@ -28,7 +28,9 @@ All notable changes to this project will be documented in this file, in reverse
 
 ### Deprecated
 
-- Nothing.
+- [#35](https://github.com/zendframework/zend-stdlib/pull/35) deprecates
+  `Zend\Stdlib\CallbackHandler`, as the one component that used it,
+  zend-eventmanager, will no longer depend on it starting in v3.
 
 ### Removed
 

src/CallbackHandler.php

@@ -17,6 +17,11 @@
  * A handler for an event, event, filterchain, etc. Abstracts PHP callbacks,
  * primarily to allow for lazy-loading and ensuring availability of default
  * arguments (currying).
+ *
+ * This was primarily used in zend-eventmanager for managing listeners; as that
+ * component removes its usage of this class for v3, it is deprecated.
+ *
+ * @deprecated as of v2.7.4.
  */
 class CallbackHandler
 {