Removed dead code; fixed phpdoc

There is a lot of undeclared properties, I've declared them and added few missing phpdocs. I've also removed dead code.
see lines like this one: https://github.com/fprochazka/php-amqplib/blob/patch-2/PhpAmqpLib/Channel/AMQPChannel.php#L531 where I think these kind of changes should be consistent