Fix SimpleActuator for (defaul,setter) properties in HTML5

SimpleActuator uses Reflect.setField() to set values. But if targetting HTML5 we have some property defined like

public var prop1 (default, _setProp1)  : Float;

Than setter for this property is never called on tweening.
Perhaps it's better to change all Reflect.setField() calls to Reflect.setProperty(). Or at least use #if html5 Reflect.setProperty() #else Reflect.setField() #end

As far as i know (however i can mistake) Reflect.setField() is not supposed to call setters or getters at all and it sets values directly to fields bypassing the setters.