COAST

AllocatorUnref should be changed to handle both Ref and Unref of the tracked allocator.
Therefor it should behave like a shared pointer tracking the lifetime of the tracked object.
The object itself should be tracked by some kind of unique_ptr, as the initially assigned fAllocator from within the contructor might change during Thread.Start().

At the same time, it should be checked if the allocator ctor argument is still in use or if we should rely on the use of the optional allocator parameter of Thread.Start().