True disposable objects (add "Finalized!" assertion)

[Steven Schveighoffer]

On Fri, 04 May 2012 14:50:06 -0400, Simen Kjaeraas  
<simen.kjaras at gmail.com> wrote:

> I believe the idea was that it'd blow up if you use it unwisely. clear  
> might
> do that, but if you're unlucky, it'll 'work' just fine, giving you  
> problems
> later.

clear zeros out the vtable, so it's highly unlikely it "just works".

-Steve