Syntax glue to get the MemPool API back in shape.

Syntax glue to get the MemPool API back in shape.

Standalone pool:
  MemAllocator *pool = memPoolCreate(name, size)

Pooled class just as before;

class XXX {
public:
  MEMPROXY_CLASS(XXX)
  ...
}

MEMPROXY_CLASS_INLINE(XXX)

The other MemAllocator derived classes is considered private and should
not be used outside MemPool.cc