Enhance CJSON with JsonSerializable support (#2540)
Encoding a JsonSerializable object will now have it's serializable result
encoded by CJSON.
Added a guard to prevent the autoload bug as mentioned by @cebe.
Added unit test.
2887 Add __isset method for CFormElement
Fix indention from spaces to tabs in CFormElement
Add bug #2887 to CHANGELOG
Merge pull request #2891 from bijibox/2887-cformelement-__isset

#2887 Add __isset method for CFormElement
Merge branch '2540-CJSON-JsonSerializable' of https://github.com/SamMousa/yii into SamMousa-2540-CJSON-JsonSerializable
Merge branch '2540-CJSON-JsonSerializable' of https://github.com/SamMousa/yii into SamMousa-2540-CJSON-JsonSerializable
Property 'CErrorHandler::exception' added to store current handling exception instance
Issue #1593 added to CHANGELOG
Added support for scopes in CStatRelation
Issue #873 added to CHANGELOG
CCaptchaAction updated to use DIRECTORY_SEPARATOR while composing font file name.
Merge pull request #2923 from klimov-paul/1593-allow-error-handler-exception-access

Fixes #1593: Allow access to exception currently processed by CErrorHandler
Merge branch 'master' of github.com:yiisoft/yii into 873-stat-relation-scopes
Merge pull request #2924 from klimov-paul/873-stat-relation-scopes

Fixes #873 stat relation scopes