CActiveRecord has been refactored: meta data objects are now stored at the static field.
Note about overriding "CActiveRecord::__construct()" has been added.
Extra "CActiveRecordMetaData::$_model" field has been removed.
Code indenting at "CActiveRecordMetaData" has been fixed.
Field "CActiveRecordMetaData::$_modelClassName" has been added to track active record class and compose verbose exception messages.
Merge pull request #2269 from klimov-paul/2251-refactor-active-record-meta-data-static

Refactor active record meta data to be static field