Duplicate  DataWriter doesn't use resolved class name

It calls resolveDynamicClass and gets back $createClass, checks it for false... and then promptly ignores it and uses the original unaltered $class when instantiating :D

Not sure if the other calls to resolveDynamicClass go ignored like this - might want to double check, or my addons will get sad really fast!

(ps - the mechanism for extending classes actually seems pretty nifty!)