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.
delay validation of scenario to validate().
Fixes issue #592: I18N t() plural forms possibly broken
added subsection to docs index
model guide
added dabase basics docs
removed dao section from docs
Update model.md
activerecord draft
Update database-basics.md
better sentence for label example.