Proposed mutex extension.
Uncomment UNIX Mutex.
Mutex extension docblocks and several minor fixes.
composer.json file and proper class files location.
Proper files location.
Mutex cache backend WIP.
Autorelease callback improved, composer.json typo.
Autorelease callback.
Fixes:

1. Proper auto release shutdown callback.
2. Proper Mutex::releaseLock() method.
Mutex WIP.
debug toolbar WIP
Improved Json::encode() security.
Enhanced ArrayHelper::toArray()
Fixed basic layout.
Removed unused code.
Fixes issue #588: Added afterValidate to ActiveForm.
Support preloading modules
Added new events.
Fixes issue #589: validate the scenario name.
Added back the events for Controller.