Fix for the use namespace problems we've been having with ASC (I hope). The problem was that the use directive was being defined after we had called finish package. The UseDirectiveNode has a pkgdef ptr, and does different things depending if that ptr is null or not. It should not be null when the UseDirective is inside the package - but since we were generating the UseDirectiveNode after we had called finishPackage the UseDirectiveNode didn't have it's pkgdef ptr set, and so things went awry as the package didn't get set up with all the correct open namespaces. I haven't tested this in authoring/flex but I am pretty sure that this will fix all the problems we're seeing.