Refactored Doctrine_Connection: separated into two different classes Doctrine_Connection and Doctrine_Transaction

Changed ValidatorUSState to conform to the standard Doctrine_Validator_* naming scheme and removed the old style from Doctrine_Validator

Doctrine_Record::getID() -> obtainIdentifier()
Doctrine_Record::setID() -> assignIdentifier()

--no commit message

added Doctrine_Access::__isset() and Doctrine_Access::__unset() for complete support of magic method invocations