HHVM compatibility: func_get_args

All func_get_args() calls have been moved to the top of the methods
because HHVM doesn't keep a copy of the original args for performance
reasons.

See facebook/hiphop-php#1027 for details.
HHVM compatibility: implement declared interfaces

HHVM does not allow declaration of interface implementation without
real implementation of methods which parameters differs from parent
class.
Fixed compatibility with PHP PDO
Fixed equal sign